# 6921 — Fastener standard equivalences: DIN to ISO / EN crossover

For 6921, fastener description is Hexagon flange bolts; iso equivalent is 8102; en iso number is 1665; interchangeability is Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted; modification notes is Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted, verified against its source on 2026-08-12.

- **DIN standard:** 6921 _(verified: appears in the quote below)_
- **Fastener description:** Hexagon flange bolts _(verified: appears in the quote below)_
- **ISO equivalent:** 8102 _(verified: appears in the quote below)_
- **EN ISO number:** 1665 _(verified: appears in the quote below)_
- **Interchangeability:** Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted _(verified: appears in the quote below)_
- **Modification notes:** Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted _(verified: appears in the quote below)_

## What the source says

> Hexagon flange bolts | 6921 | | 1665 | | 8102 | 1998-11 | Hexagon bolts with flange, heavy series | Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted |

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Fastener description

fullerfasteners.com says fastener description is **Hexagon flange bolts**, as of 2026-08-12.

> Hexagon flange bolts | 6921 | | 1665 | | 8102 | 1998-11 | Hexagon bolts with flange, heavy series | Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says fastener description is **Flange OD/serrations/tolerance windows.**, as of 2026-08-12.

> DIN 6921 | DIN EN 1665 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners

trfastenings.com says fastener description is **Hexagon Flange Bolts**, as of 2026-08-12.

> DIN 6921 | ISO 1665 | | Hexagon Flange Bolts |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


### ISO equivalent

fullerfasteners.com says iso equivalent is **8102**, as of 2026-08-12.

> Hexagon flange bolts | 6921 | | 1665 | | 8102 | 1998-11 | Hexagon bolts with flange, heavy series | Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says iso equivalent is **1665**, as of 2026-08-12.

> DIN 6921 | DIN EN 1665 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners

trfastenings.com says iso equivalent is **1665**, as of 2026-08-12.

> DIN 6921 | ISO 1665 | | Hexagon Flange Bolts |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


### Interchangeability

fullerfasteners.com says interchangeability is **Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted**, as of 2026-08-12.

> Hexagon flange bolts | 6921 | | 1665 | | 8102 | 1998-11 | Hexagon bolts with flange, heavy series | Dimensions partially changed; width across flats according to ISO 272; strength 12.9 omitted |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says interchangeability is **Check spec**, as of 2026-08-12.

> DIN 6921 | DIN EN 1665 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners


## Source

- https://fullerfasteners.com/tech/din-iso-en-crossover-chart/
- https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners
- https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards

Last verified: 2026-08-12. Review by: 2028-08-11.
Part of [Fastener standard equivalences: DIN to ISO / EN crossover](https://referencesource.org/fastener-thread-standard-equivalence/).