Dimensional specifications for NPT and BSP pipe thread sizes used in plumbing, hydraulic, and gas fittings worldwide. For each nominal pipe size within each standard, gives threads per inch, pitch, major diameter, and minor diameter — the numbers needed to identify an unknown thread or confirm whether two fittings will mate. Combines American (ASME B1.20.1) and British/ISO (ISO 228, ISO 7) standards in one table so the critical differences are visible side by side.

factual compilation of thread dimensions from public reference sources; facts cited with attributed quotes, no standard document reproduced

Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 1 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 47.80

**Minor diameter (mm):** 44.85

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4538> BSPT Rp 1 1/2 | 1 1/2" | 11 | 2.309 | 12.7 | 0 | 47.80 | 46.32 | 44.85 | 0.180 | 45.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4539> BSPT Rp 2 | 2" | 11 | 2.309 | 15.9 | 0 | 59.61 | 58.14 | 56.66 | 0.180 | 56.4 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4540> BSPT Rp 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 0 | 75.18 | 73.71 | 72.23 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4541> BSPT Rp 3 | 3" | 11 | 2.309 | 20.6 | 0 | 87.88 | 86.41 | 84.93 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4542> BSPT Rp 4 | 4" | 11 | 2.309 | 25.4 | 0 | 113.03 | 111.55 | 110.07 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4543> BSPT Rp 5 | 5" | 11 | 2.309 | 28.6 | 0 | 138.43 | 136.95 | 135.47 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4544> BSPT Rp 6 | 6" | 11 | 2.309 | 28.6 | 0 | 163.83 | 162.35 | 160.87 | 0.216 | -999 | Tolerances and Inspection The ISO 7-1 provides tolerances only for the following dimensions:

Source: <https://www.machiningdoctor.com/charts/bsp/>

1 1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 1-1/2

**Threads per inch (TPI):** 11 1/2

**Thread pitch (mm):** 2.2087

**Major (outside) diameter (mm):** 48.2600

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1.900 | 48.2600 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

1-1/2 — Plumbing fitting and pipe thread standards

governing_standard, nominal_size, thread_angle_degrees, thread_pitch_mm, thread_standard, threads_per_inch


**Thread standard:** BSPP

**Nominal size:** 1 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 47.803

**Minor diameter (mm):** 44.846

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1 1/2 | 1 1/2" | 11 | 2.309 | 47.803 | 46.324 | 44.846

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1-1/2 Inch BSP

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 47.80

> 1-1/2 Inch BSP | 47.80 mm | 45.5 mm | 11

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1-1/2 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1-1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 47.803

**Minor diameter (mm):** 44.845

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1½ | 11 | 2.309 | 1.479 | 47.803 | 46.324 | 44.845 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>

governing_standard, nominal_size, thread_angle_degrees, thread_standard


**Thread standard:** BSPT

**Nominal size:** 1 1/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 41.91

**Minor diameter (mm):** 38.95

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4537> BSPT Rp 1 1/4 | 1 1/4" | 11 | 2.309 | 12.7 | 0 | 41.91 | 40.43 | 38.95 | 0.180 | 39.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4538> BSPT Rp 1 1/2 | 1 1/2" | 11 | 2.309 | 12.7 | 0 | 47.80 | 46.32 | 44.85 | 0.180 | 45.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4539> BSPT Rp 2 | 2" | 11 | 2.309 | 15.9 | 0 | 59.61 | 58.14 | 56.66 | 0.180 | 56.4 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4540> BSPT Rp 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 0 | 75.18 | 73.71 | 72.23 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4541> BSPT Rp 3 | 3" | 11 | 2.309 | 20.6 | 0 | 87.88 | 86.41 | 84.93 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4542> BSPT Rp 4 | 4" | 11 | 2.309 | 25.4 | 0 | 113.03 | 111.55 | 110.07 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4543> BSPT Rp 5 | 5" | 11 | 2.309 | 28.6 | 0 | 138.43 | 136.95 | 135.47 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4544> BSPT Rp 6 | 6" | 11 | 2.309 | 28.6 | 0 | 163.83 | 162.35 | 160.87 | 0.216 | -999 | Tolerances and Inspection The ISO 7-1 provides tolerances only for the following dimensions:

Source: <https://www.machiningdoctor.com/charts/bsp/>

1 1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 1-1/4

**Threads per inch (TPI):** 11 1/2

**Thread pitch (mm):** 2.2087

**Major (outside) diameter (mm):** 42.1640

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1.660 | 42.1640 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

1-1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPP

**Nominal size:** 1 1/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 41.910

**Minor diameter (mm):** 38.953

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1 1/4 | 1 1/4" | 11 | 2.309 | 41.910 | 40.431 | 38.953

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1-1/4 Inch BSP

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 41.91

> 1-1/4 Inch BSP | 41.91 mm | 39.6 mm | 11

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1-1/4 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1-1/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 41.910

**Minor diameter (mm):** 38.952

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1¼ | 11 | 2.309 | 1.479 | 41.910 | 40.431 | 38.952 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 1 1/8

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 37.897

**Minor diameter (mm):** 34.940

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1 1/8 | 1 1/8" | 11 | 2.309 | 37.897 | 36.418 | 34.940

Source: <https://www.machiningdoctor.com/charts/bsp/>

1 1/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1-1/8

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 37.897

**Minor diameter (mm):** 34.939

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1.4920 | 37.897

Source: <https://en.wikipedia.org/wiki/British_Standard_Pipe>

1-1/8 — Plumbing fitting and pipe thread standards

governing_standard, minor_diameter_mm, nominal_size, thread_angle_degrees, thread_pitch_mm, thread_standard, threads_per_inch


**Thread standard:** BSPP

**Nominal size:** 1

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 33.249

**Minor diameter (mm):** 30.292

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1 | 1" | 11 | 2.309 | 33.249 | 31.770 | 30.292

Source: <https://www.machiningdoctor.com/charts/bsp/>

1 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 1/16

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 7.72

**Minor diameter (mm):** 6.56

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> 111.55 | 110.07 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4513> BSPT R 5 | 5" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 138.43 | 136.95 | 135.47 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4514> BSPT R 6 | 6" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 163.83 | 162.35 | 160.87 | 0 | -999.00 | BSPT Rc (Internal Tapered) Dimensions Chart Dimensions are in millimeters . To view Inch values, click the Thread Description . The below chart shows only the main dimensions. To view all the dimensions, click the thread description or use the <https://www.machiningdoctor.com/calculators/threading/?fam=BSPT&ser=Rc> BSPT Thread Calculator . series | Thread | Pipe OD | TPI | Pitch | Gauge Length | Tol (Turns/mm) | Major Diam | Pitch Diam | Minor Diam | Fit Allowance (Turns/mm) | Tap Drill Size | Rc | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4515> BSPT Rc 1/16 | 1/16" | 28 | 0.907 | 4.0 | 1.25 / 1.1 | 7.72 | 7.14 | 6.56 |

Source: <https://www.machiningdoctor.com/charts/bsp/>

1/16 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 1/16

**Threads per inch (TPI):** 27

**Thread pitch (mm):** 0.9407

**Major (outside) diameter (mm):** 7.950

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 0.313 | 7.950 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** BSPP

**Nominal size:** 1/16

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 7.723

**Minor diameter (mm):** 6.561

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1/16 | 1/16" | 28 | 0.907 | 7.723 | 7.142 | 6.561

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1/16

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 7.723

**Minor diameter (mm):** 6.561

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/16 | 28 | 0.907 | 0.581 | 7.723 | 7.142 | 6.561 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSP

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 20.955

**Minor diameter (mm):** 18.633

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/2 | 14 | 0.0714 | 1.814 | 0.825 | 20.955 | 0.7336 | 18.633 | 0.3214 | 8.164

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 20.96

**Minor diameter (mm):** 18.63

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> 20.96 | 19.79 | 18.63 | 0.142 | 18.5 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4535> BSPT Rp 3/4 | 3/4" | 14 | 1.814 | 9.5 | 0 | 26.44 | 25.28 | 24.12 | 0.142 | 24.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4536> BSPT Rp 1 | 1" | 11 | 2.309 | 10.4 | 0 | 33.25 | 31.77 | 30.29 | 0.180 | 30.2 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4537> BSPT Rp 1 1/4 | 1 1/4" | 11 | 2.309 | 12.7 | 0 | 41.91 | 40.43 | 38.95 | 0.180 | 39.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4538> BSPT Rp 1 1/2 | 1 1/2" | 11 | 2.309 | 12.7 | 0 | 47.80 | 46.32 | 44.85 | 0.180 | 45.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4539> BSPT Rp 2 | 2" | 11 | 2.309 | 15.9 | 0 | 59.61 | 58.14 | 56.66 | 0.180 | 56.4 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4540> BSPT Rp 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 0 | 75.18 | 73.71 | 72.23 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4541> BSPT Rp 3 | 3" | 11 | 2.309 | 20.6 | 0 | 87.88 | 86.41 | 84.93 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4542> BSPT Rp 4 | 4" | 11 | 2.309 | 25.4 | 0 | 113.03 | 111.55 | 110.07 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4543> BSPT Rp 5 | 5" | 11 | 2.309 | 28.6 | 0 | 138.43 | 136.95 | 135.47 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4544> BSPT Rp 6 | 6" | 11 | 2.309 | 28.6 | 0 | 163.83 | 162.35 | 160.87 | 0.216 | -999 | Tolerances and Inspection The ISO 7-1 provides tolerances only for the following dimensions:

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** NPT

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.8143

**Major (outside) diameter (mm):** 21.3360

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 0.840 | 21.3360 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.81432

**Major (outside) diameter (mm):** 21.34

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1/2 | 14 | 0.07143 | 1.81432 | 0.84 | 21.34

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 20.955

**Minor diameter (mm):** 18.632

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1/2 | 1/2" | 14 | 1.814 | 20.955 | 19.793 | 18.632

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1/2 Inch BSP

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 20.99

> 1/2 Inch BSP | 20.99 mm | 19.1 mm | 14

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1/2 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 20.955

**Minor diameter (mm):** 18.631

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/2 | 14 | 1.814 | 1.162 | 20.955 | 19.793 | 18.631 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** NPT

**Nominal size:** 1¼

**Threads per inch (TPI):** 11½

**Thread pitch (mm):** 2.20878

**Major (outside) diameter (mm):** 42.16

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1¼ | 11½ | 0.08696 | 2.20878 | 1.66 | 42.16

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

1¼ — Plumbing fitting and pipe thread standards


**Thread standard:** BSPP

**Nominal size:** 1 3/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 53.746

**Minor diameter (mm):** 50.789

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1 3/4 | 1 3/4" | 11 | 2.309 | 53.746 | 52.267 | 50.789

Source: <https://www.machiningdoctor.com/charts/bsp/>

1 3/4 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 1

**Threads per inch (TPI):** 11 1/2

**Thread pitch (mm):** 2.2087

**Major (outside) diameter (mm):** 33.4010

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1.315 | 33.4010 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

governing_standard, thread_angle_degrees, thread_pitch_mm, thread_standard, threads_per_inch


**Thread standard:** BSP

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 13.157

**Minor diameter (mm):** 11.445

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/4 | 19 | 0.0526 | 1.337 | 0.517 | 13.157 | 0.4506 | 11.445 | 0.2367 | 6.012

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 13.16

**Minor diameter (mm):** 11.45

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> 13.16 | 12.30 | 11.45 | 0.104 | 11.5 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4533> BSPT Rp 3/8 | 3/8" | 19 | 1.337 | 6.4 | 0 | 16.66 | 15.81 | 14.95 | 0.104 | 15.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4534> BSPT Rp 1/2 | 1/2" | 14 | 1.814 | 8.2 | 0 | 20.96 | 19.79 | 18.63 | 0.142 | 18.5 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4535> BSPT Rp 3/4 | 3/4" | 14 | 1.814 | 9.5 | 0 | 26.44 | 25.28 | 24.12 | 0.142 | 24.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4536> BSPT Rp 1 | 1" | 11 | 2.309 | 10.4 | 0 | 33.25 | 31.77 | 30.29 | 0.180 | 30.2 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4537> BSPT Rp 1 1/4 | 1 1/4" | 11 | 2.309 | 12.7 | 0 | 41.91 | 40.43 | 38.95 | 0.180 | 39.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4538> BSPT Rp 1 1/2 | 1 1/2" | 11 | 2.309 | 12.7 | 0 | 47.80 | 46.32 | 44.85 | 0.180 | 45.0 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4539> BSPT Rp 2 | 2" | 11 | 2.309 | 15.9 | 0 | 59.61 | 58.14 | 56.66 | 0.180 | 56.4 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4540> BSPT Rp 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 0 | 75.18 | 73.71 | 72.23 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4541> BSPT Rp 3 | 3" | 11 | 2.309 | 20.6 | 0 | 87.88 | 86.41 | 84.93 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4542> BSPT Rp 4 | 4" | 11 | 2.309 | 25.4 | 0 | 113.03 | 111.55 | 110.07 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4543> BSPT Rp 5 | 5" | 11 | 2.309 | 28.6 | 0 | 138.43 | 136.95 | 135.47 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4544> BSPT Rp 6 | 6" | 11 | 2.309 | 28.6 | 0 | 163.83 | 162.35 | 160.87 | 0.216 | -999 | Tolerances and Inspection The ISO 7-1 provides tolerances only for the following dimensions:

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** NPT

**Nominal size:** 1/4

**Threads per inch (TPI):** 18

**Thread pitch (mm):** 1.4111

**Major (outside) diameter (mm):** 13.716

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 0.540 | 13.716 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 1/4

**Threads per inch (TPI):** 18

**Thread pitch (mm):** 1.41122

**Major (outside) diameter (mm):** 13.72

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1/4 | 18 | 0.05556 | 1.41122 | 0.54 | 13.72

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 13.157

**Minor diameter (mm):** 11.445

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1/4 | 1/4" | 19 | 1.337 | 13.157 | 12.301 | 11.445

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1/4 Inch BSP

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 13.16

> 1/4 Inch BSP | 13.16 mm | 11.9mm | 19

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1/4 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 13.157

**Minor diameter (mm):** 11.445

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/4 | 19 | 1.337 | 0.856 | 13.157 | 12.301 | 11.445 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** NPT

**Nominal size:** 1½

**Threads per inch (TPI):** 11½

**Thread pitch (mm):** 2.20878

**Major (outside) diameter (mm):** 48.26

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1½ | 11½ | 0.08695 | 2.20878 | 1.9 | 48.26

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

1½ — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 33.249

**Minor diameter (mm):** 30.292

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1 | 11 | 0.0909 | 2.309 | 1.309 | 33.249 | 1.1926 | 30.292 | 0.4091 | 10.391

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSP

**Nominal size:** 1¼

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 41.91

**Minor diameter (mm):** 38.953

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1¼ | 11 | 0.0909 | 2.309 | 1.65 | 41.91 | 1.5336 | 38.953 | 0.5 | 12.7

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSP

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 9.728

**Minor diameter (mm):** 8.565

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/8 | 28 | 0.0357 | 0.907 | 0.383 | 9.728 | 0.3372 | 8.565 | 0.1563 | 3.97

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

1/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 9.73

**Minor diameter (mm):** 8.57

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> 111.55 | 110.07 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4513> BSPT R 5 | 5" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 138.43 | 136.95 | 135.47 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4514> BSPT R 6 | 6" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 163.83 | 162.35 | 160.87 | 0 | -999.00 | BSPT Rc (Internal Tapered) Dimensions Chart Dimensions are in millimeters . To view Inch values, click the Thread Description . The below chart shows only the main dimensions. To view all the dimensions, click the thread description or use the <https://www.machiningdoctor.com/calculators/threading/?fam=BSPT&ser=Rc> BSPT Thread Calculator . series | Thread | Pipe OD | TPI | Pitch | Gauge Length | Tol (Turns/mm) | Major Diam | Pitch Diam | Minor Diam | Fit Allowance (Turns/mm) | Tap Drill Size | Rc | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4515> BSPT Rc 1/16 | 1/16" | 28 | 0.907 | 4.0 | 1.25 / 1.1 | 7.72 | 7.14 | 6.56 | 0 | 6.4 | Rc | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4516> BSPT Rc 1/8 | 1/8" | 28 | 0.907 | 4.0 | 1.25 / 1.1 | 9.73 | 9.15 | 8.57 |

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** NPT

**Nominal size:** 1/8

**Threads per inch (TPI):** 27

**Thread pitch (mm):** 0.9407

**Major (outside) diameter (mm):** 10.287

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 0.405 | 10.287 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 1/8

**Threads per inch (TPI):** 27

**Thread pitch (mm):** 0.94082

**Major (outside) diameter (mm):** 10.29

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1/8 | 27 | 0.03704 | 0.94082 | 0.405 | 10.29

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 9.728

**Minor diameter (mm):** 8.566

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 1/8 | 1/8" | 28 | 0.907 | 9.728 | 9.147 | 8.566

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 1/8 Inch BSP

**Threads per inch (TPI):** 28

**Major (outside) diameter (mm):** 9.7

> 1/8 Inch BSP | 9.7 mm | 8.9 mm | 28

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1/8 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Thread pitch (mm):** 0.907

**Major (outside) diameter (mm):** 9.728

**Minor diameter (mm):** 8.566

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1/8 | 28 | 0.907 | 0.581 | 9.728 | 9.147 | 8.566 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSP

**Nominal size:** 1½

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 46.803

**Minor diameter (mm):** 44.846

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1½ | 11 | 0.0909 | 2.309 | 1.882 | 46.803 | 1.7656 | 44.846 | 0.5 | 12.7

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSP

**Nominal size:** 1 Inch BSP

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 33.25

> 1 Inch BSP | 33.25 mm | 31.0 mm | 11

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

1 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 33.249

**Minor diameter (mm):** 30.291

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1 | 11 | 2.309 | 1.479 | 33.249 | 31.770 | 30.291 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** NPT

**Nominal size:** 10

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 273.0500

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 10.750 | 273.0500 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

10 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 12

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 323.8500

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 12.750 | 323.8500 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

12 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 2 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 75.18

**Minor diameter (mm):** 72.23

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4540> BSPT Rp 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 0 | 75.18 | 73.71 | 72.23 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4541> BSPT Rp 3 | 3" | 11 | 2.309 | 20.6 | 0 | 87.88 | 86.41 | 84.93 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4542> BSPT Rp 4 | 4" | 11 | 2.309 | 25.4 | 0 | 113.03 | 111.55 | 110.07 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4543> BSPT Rp 5 | 5" | 11 | 2.309 | 28.6 | 0 | 138.43 | 136.95 | 135.47 | 0.216 | -999 | Rp | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4544> BSPT Rp 6 | 6" | 11 | 2.309 | 28.6 | 0 | 163.83 | 162.35 | 160.87 | 0.216 | -999 | Tolerances and Inspection The ISO 7-1 provides tolerances only for the following dimensions:

Source: <https://www.machiningdoctor.com/charts/bsp/>

2 1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 2-1/2

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 73.0250

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 2.875 | 73.0250 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

2-1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPP

**Nominal size:** 2 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 75.184

**Minor diameter (mm):** 72.227

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 2 1/2 | 2 1/2" | 11 | 2.309 | 75.184 | 73.705 | 72.227

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 2-1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 75.184

**Minor diameter (mm):** 72.226

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 2½ | 11 | 2.309 | 1.479 | 75.184 | 73.705 | 72.226 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 2 1/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 65.710

**Minor diameter (mm):** 62.753

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 2 1/4 | 2 1/4" | 11 | 2.309 | 65.710 | 64.231 | 62.753

Source: <https://www.machiningdoctor.com/charts/bsp/>

2 1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 2½

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.175

**Major (outside) diameter (mm):** 73.03

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 2½ | 8 | 0.125 | 3.175 | 2.875 | 73.03

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

2½ — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 2

**Threads per inch (TPI):** 11 1/2

**Thread pitch (mm):** 2.2087

**Major (outside) diameter (mm):** 60.3250

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 2.375 | 60.3250 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

2 — Plumbing fitting and pipe thread standards

governing_standard, thread_pitch_mm, thread_standard, threads_per_inch


**Thread standard:** BSPP

**Nominal size:** 2 3/4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 81.534

**Minor diameter (mm):** 78.577

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 2 3/4 | 2 3/4" | 11 | 2.309 | 81.534 | 80.055 | 78.577

Source: <https://www.machiningdoctor.com/charts/bsp/>

2 3/4 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 2

**Threads per inch (TPI):** 11½

**Thread pitch (mm):** 2.20878

**Major (outside) diameter (mm):** 60.33

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 2 | 11½ | 0.08696 | 2.20878 | 2.375 | 60.33

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSP

**Nominal size:** 2½

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 75.184

**Minor diameter (mm):** 72.227

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 2½ | 11 | 0.0909 | 2.309 | 2.96 | 75.184 | 2.8436 | 72.227 | 0.6875 | 17.463

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 59.614

**Minor diameter (mm):** 56.657

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 2 | 2" | 11 | 2.309 | 59.614 | 58.135 | 56.657

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 2 Inch BSP

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 59.61

> 2 Inch BSP | 59.61 mm | 57.4 mm | 11

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

2 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 59.614

**Minor diameter (mm):** 56.656

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 2 | 11 | 2.309 | 1.479 | 59.614 | 58.135 | 56.656 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 3 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 100.330

**Minor diameter (mm):** 97.373

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 3 1/2 | 3 1/2" | 11 | 2.309 | 100.330 | 98.851 | 97.373

Source: <https://www.machiningdoctor.com/charts/bsp/>

3 1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 3-1/2

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 101.6000

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 4.000 | 101.6000 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

3-1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 3

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 87.884

**Minor diameter (mm):** 84.927

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3 | 11 | 0.0909 | 2.309 | 3.46 | 87.884 | 3.3436 | 84.927 | 0.8125 | 20.638

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

3 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 3

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 88.9000

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 3.500 | 88.9000 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 3

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.175

**Major (outside) diameter (mm):** 88.9

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 3 | 8 | 0.125 | 3.175 | 3.5 | 88.9

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSP

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 26.441

**Minor diameter (mm):** 24.12

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3/4 | 14 | 0.0714 | 1.814 | 1.041 | 26.441 | 0.9496 | 24.12 | 0.375 | 9.525

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

3/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 26.44

**Minor diameter (mm):** 24.12

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4505> BSPT R 3/4 | 3/4" | 14 | 1.814 | 9.5 | 1.0 / 1.8 | 26.44 | 25.28 | 24.12 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4506> BSPT R 1 | 1" | 11 | 2.309 | 10.4 | 1.0 / 2.3 | 33.25 | 31.77 | 30.29 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4507> BSPT R 1 1/4 | 1 1/4" | 11 | 2.309 | 12.7 | 1.0 / 2.3 | 41.91 | 40.43 | 38.95 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4508> BSPT R 1 1/2 | 1 1/2" | 11 | 2.309 | 12.7 | 1.0 / 2.3 | 47.80 | 46.32 | 44.85 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4509> BSPT R 2 | 2" | 11 | 2.309 | 15.9 | 1.0 / 2.3 | 59.61 | 58.14 | 56.66 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4510> BSPT R 2 1/2 | 2 1/2" | 11 | 2.309 | 17.5 | 1.5 / 3.5 | 75.18 | 73.71 | 72.23 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4511> BSPT R 3 | 3" | 11 | 2.309 | 20.6 | 1.5 / 3.5 | 87.88 | 86.41 | 84.93 | 0 | -999.00 | R | <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4512> BSPT R 4 | 4" | 11 | 2.309 | 25.4 | 1.5 / 3.5 | 113.03 | 111.55 |

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** NPT

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.8143

**Major (outside) diameter (mm):** 26.6700

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 1.050 | 26.6700 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.81432

**Major (outside) diameter (mm):** 26.67

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 3/4 | 14 | 0.07143 | 1.81432 | 1.05 | 26.67

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 26.441

**Minor diameter (mm):** 24.118

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 3/4 | 3/4" | 14 | 1.814 | 26.441 | 25.279 | 24.118

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 3/4 Inch BSP

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 26.44

> 3/4 Inch BSP | 26.44 mm | 24.6 mm | 14

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

3/4 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 26.441

**Minor diameter (mm):** 24.117

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3/4 | 14 | 1.814 | 1.162 | 26.441 | 25.279 | 24.117 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 3

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 87.884

**Minor diameter (mm):** 84.927

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 3 | 3" | 11 | 2.309 | 87.884 | 86.405 | 84.927

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 16.662

**Minor diameter (mm):** 14.95

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3/8 | 19 | 0.0526 | 1.337 | 0.656 | 16.662 | 0.5886 | 14.95 | 0.25 | 6.25

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

3/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 16.66

**Minor diameter (mm):** 14.95

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> <https://www.machiningdoctor.com/threadinfo-bspt/?tid=4503> BSPT R 3/8 | 3/8" | 19 | 1.337 | 6.4 | 1.0 / 1.3 | 16.66 | 15.81 | 14.95 |

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** NPT

**Nominal size:** 3/8

**Threads per inch (TPI):** 18

**Thread pitch (mm):** 1.4111

**Major (outside) diameter (mm):** 17.145

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 0.675 | 17.145 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 3/8

**Threads per inch (TPI):** 18

**Thread pitch (mm):** 1.41122

**Major (outside) diameter (mm):** 17.15

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 3/8 | 18 | 0.05556 | 1.41122 | 0.675 | 17.15

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 16.662

**Minor diameter (mm):** 14.950

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 3/8 | 3/8" | 19 | 1.337 | 16.662 | 15.806 | 14.950

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 3/8 Inch BSP

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 16.66

> 3/8 Inch BSP | 16.66 mm | 15.2 mm | 19

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

3/8 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Thread pitch (mm):** 1.337

**Major (outside) diameter (mm):** 16.662

**Minor diameter (mm):** 14.950

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3/8 | 19 | 1.337 | 0.856 | 16.662 | 15.806 | 14.950 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSP

**Nominal size:** 3

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 87.884

**Minor diameter (mm):** 84.926

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 3 | 11 | 2.309 | 1.479 | 87.884 | 86.405 | 84.926 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 4 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 125.730

**Minor diameter (mm):** 122.773

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 4 1/2 | 4 1/2" | 11 | 2.309 | 125.730 | 124.251 | 122.773

Source: <https://www.machiningdoctor.com/charts/bsp/>

4 1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 113.03

**Minor diameter (mm):** 110.073

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 4 | 11 | 0.0909 | 2.309 | 4.45 | 113.03 | 4.3336 | 110.073 | N/A | N/A

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>

4 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 4

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 114.3000

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 4.500 | 114.3000 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 4

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.175

**Major (outside) diameter (mm):** 114.3

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 4 | 8 | 0.125 | 3.175 | 4.5 | 114.3

Source: <https://www.geminivalve.com/bsp-thread-vs-npt-fitting/>


**Thread standard:** BSPP

**Nominal size:** 4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 113.030

**Minor diameter (mm):** 110.073

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 4 | 4" | 11 | 2.309 | 113.030 | 111.551 | 110.073

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 113.030

**Minor diameter (mm):** 110.072

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 4 | 11 | 2.309 | 1.479 | 113.030 | 111.551 | 110.072 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 5 1/2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 151.130

**Minor diameter (mm):** 148.173

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 5 1/2 | 5 1/2" | 11 | 2.309 | 151.130 | 149.651 | 148.173

Source: <https://www.machiningdoctor.com/charts/bsp/>

5 1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 5

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 138.430

**Minor diameter (mm):** 135.472

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 5.4500 | 138.430

Source: <https://en.wikipedia.org/wiki/British_Standard_Pipe>

5 — Plumbing fitting and pipe thread standards

governing_standard, minor_diameter_mm, thread_angle_degrees, thread_pitch_mm, thread_standard, threads_per_inch


**Thread standard:** BSPP

**Nominal size:** 5

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 138.430

**Minor diameter (mm):** 135.473

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 5 | 5" | 11 | 2.309 | 138.430 | 136.951 | 135.473

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSPP

**Nominal size:** 5/8

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 22.911

**Minor diameter (mm):** 20.588

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 5/8 | 5/8" | 14 | 1.814 | 22.911 | 21.749 | 20.588

Source: <https://www.machiningdoctor.com/charts/bsp/>

5/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 5/8 Inch BSP

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 22.99

> 5/8 Inch BSP | 22.99 mm | 20.3 mm | 14

Source: <https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained>

5/8 Inch BSP — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 5/8

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 22.911

**Minor diameter (mm):** 20.587

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 0.9020 | 22.911

Source: <https://en.wikipedia.org/wiki/British_Standard_Pipe>


**Thread standard:** NPT

**Nominal size:** 5

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 141.3002

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 5.563 | 141.3002 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>


**Thread standard:** NPT

**Nominal size:** 6

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 168.2750

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 6.625 | 168.2750 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

6 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPP

**Nominal size:** 6

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 163.830

**Minor diameter (mm):** 160.873

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 6 | 6" | 11 | 2.309 | 163.830 | 162.351 | 160.873

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSP

**Nominal size:** 6

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 163.830

**Minor diameter (mm):** 160.872

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 6 | 11 | 2.309 | 1.479 | 163.830 | 162.351 | 160.872 |

Source: <https://amesweb.info/Screws/BSP-Thread-Chart.aspx>


**Thread standard:** BSPP

**Nominal size:** 7/8

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 30.201

**Minor diameter (mm):** 27.878

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> BSPP G 7/8 | 7/8" | 14 | 1.814 | 30.201 | 29.039 | 27.878

Source: <https://www.machiningdoctor.com/charts/bsp/>

7/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 7/8

**Threads per inch (TPI):** 14

**Thread pitch (mm):** 1.814

**Major (outside) diameter (mm):** 30.201

**Minor diameter (mm):** 27.877

**Thread angle (degrees):** 55

**Governing standard:** ISO 228-1

> 1.1890 | 30.201

Source: <https://en.wikipedia.org/wiki/British_Standard_Pipe>


**Thread standard:** NPT

**Nominal size:** 8

**Threads per inch (TPI):** 8

**Thread pitch (mm):** 3.1750

**Major (outside) diameter (mm):** 219.0750

**Thread angle (degrees):** 60

**Governing standard:** ASME B1.20.1

> 8.625 | 219.0750 |

Source: <https://en.wikipedia.org/wiki/National_pipe_thread>

8 — Plumbing fitting and pipe thread standards

governing_standard, thread_angle_degrees, thread_pitch_mm, thread_standard


**Thread standard:** BSP

**Nominal size:** 1-1/2

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 47.80

> 1-1/2 Inch BSP | 47.80 mm / 1-3/4" | 11

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>

1-1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1-1/4

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 41.91

> 1-1/4 Inch BSP | 41.91 mm / 1.-1/2" | 11

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>

1-1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 20.8

> -08 (1/2) | 14 | 20.8 | 0.82 | 19.1 | 0.75

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

1/2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 20.99

> 1/2 Inch BSP | 20.99 mm / 3/4" | 14

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 1 ¼

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 41.9

> -20 (1 ¼) | 11 | 41.9 | 1.65 | 39.6 | 1.56

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

1 ¼ — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 13.2

> -04 (1/4) | 19 | 13.2 | 0.52 | 11.9 | 0.47

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

1/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/4

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 13.16

> 1/4 Inch BSP | 13.16 mm / 1/2" | 19

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 1 ½

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 47.8

> -24 (1 ½) | 11 | 47.8 | 1.88 | 45.5 | 1.79

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

1 ½ — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Major (outside) diameter (mm):** 9.7

> -02 (1/8) | 28 | 9.7 | 0.38 | 8.9 | 0.35

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

1/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 1/8

**Threads per inch (TPI):** 28

**Major (outside) diameter (mm):** 9.52

> 1/8 Inch BSP | 9.52 mm / 3/8" | 28

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 1

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 33.25

> 1 Inch BSP | 33.25 mm / 1-1/4" | 11

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>

1 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 2

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 59.7

> -32 (2) | 11 | 59.7 | 2.35 | 57.4 | 2.26

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

2 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 2

**Threads per inch (TPI):** 11

**Major (outside) diameter (mm):** 59.61

> 2 Inch BSP | 59.61 mm / 2-1/4" | 11

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 26.4

> -12 (3/4) | 14 | 26.4 | 1.04 | 24.6 | 0.97

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

3/4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 26.44

> 3/4 Inch BSP | 26.44 mm / 1" | 14

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 16.5

> -06 (3/8) | 19 | 16.5 | 0.65 | 15.2 | 0.60

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

3/8 — Plumbing fitting and pipe thread standards


**Thread standard:** BSP

**Nominal size:** 3/8

**Threads per inch (TPI):** 19

**Major (outside) diameter (mm):** 16.66

> 3/8 Inch BSP | 16.66 mm / 5/8" | 19

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSP

**Nominal size:** 5/8

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 22.4

> -10 (5/8) | 14 | 22.4 | 0.88 | 20.3 | 0.80

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** BSP

**Nominal size:** 5/8

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 22.99

> 5/8 Inch BSP | 22.99 mm / 7/8" | 14

Source: <https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings>


**Thread standard:** BSPT

**Nominal size:** 1

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 33.25

**Minor diameter (mm):** 30.29

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 1 | 1" | 11 | 2.309 | 10.4 | 1.0 / 2.3 | 33.25 | 31.77 | 30.29 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSPT

**Nominal size:** 2

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 59.61

**Minor diameter (mm):** 56.66

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 2 | 2" | 11 | 2.309 | 15.9 | 1.0 / 2.3 | 59.61 | 58.14 | 56.66 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>


**Thread standard:** BSPT

**Nominal size:** 3

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 87.88

**Minor diameter (mm):** 84.93

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 3 | 3" | 11 | 2.309 | 20.6 | 1.5 / 3.5 | 87.88 | 86.41 | 84.93 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>

3 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 4

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 113.03

**Minor diameter (mm):** 110.07

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 4 | 4" | 11 | 2.309 | 25.4 | 1.5 / 3.5 | 113.03 | 111.55 | 110.07 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>

4 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 5

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 138.43

**Minor diameter (mm):** 135.47

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 5 | 5" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 138.43 | 136.95 | 135.47 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>

5 — Plumbing fitting and pipe thread standards


**Thread standard:** BSPT

**Nominal size:** 6

**Threads per inch (TPI):** 11

**Thread pitch (mm):** 2.309

**Major (outside) diameter (mm):** 163.83

**Minor diameter (mm):** 160.87

**Thread angle (degrees):** 55

**Governing standard:** ISO 7-1

> BSPT R 6 | 6" | 11 | 2.309 | 28.6 | 1.5 / 3.5 | 163.83 | 162.35 | 160.87 | 0 | -999.00

Source: <https://www.machiningdoctor.com/charts/bsp/>

6 — Plumbing fitting and pipe thread standards


**Thread standard:** NPT

**Nominal size:** 1/2

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 21.3

> -08 (1/2) | 14 | 21.3 | 0.84 | 19.3 | 0.76

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 1 ¼

**Threads per inch (TPI):** 11½

**Major (outside) diameter (mm):** 42.2

> -20 (1 ¼) | 11½ | 42.2 | 1.66 | 40.1 | 1.58

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 1/4

**Threads per inch (TPI):** 18

**Major (outside) diameter (mm):** 13.7

> -04 (1/4) | 18 | 13.7 | 0.54 | 12.4 | 0.49

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 1 ½

**Threads per inch (TPI):** 11½

**Major (outside) diameter (mm):** 48.3

> -24 (1 ½) | 11½ | 48.3 | 1.90 | 46.2 | 1.82

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 1/8

**Threads per inch (TPI):** 27

**Major (outside) diameter (mm):** 10.3

> -02 (1/8) | 27 | 10.3 | 0.41 | 9.4 | 0.37

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 1

**Threads per inch (TPI):** 11½

**Major (outside) diameter (mm):** 33.3

> -16 (1) | 11½ | 33.3 | 1.31 | 31.5 | 1.24

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 2

**Threads per inch (TPI):** 11½

**Major (outside) diameter (mm):** 60.4

> -32 (2) | 11½ | 60.4 | 2.38 | 57.9 | 2.29

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 3/4

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 26.9

> -12 (3/4) | 14 | 26.9 | 1.06 | 24.9 | 0.98

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 3/8

**Threads per inch (TPI):** 18

**Major (outside) diameter (mm):** 17.3

> -06 (3/8) | 18 | 17.3 | 0.68 | 15.7 | 0.62

Source: <https://trimantec.com/blogs/t/thread-identification-guide>


**Thread standard:** NPT

**Nominal size:** 5/8

**Threads per inch (TPI):** 14

**Major (outside) diameter (mm):** 22.9

> -10 (5/8) | 14 | 22.9 | 0.90 | 21.1 | 0.83

Source: <https://trimantec.com/blogs/t/thread-identification-guide>

5/8 — Plumbing fitting and pipe thread standards