Hypodermic needle gauge dimensions (OD, ID, wall thickness, dead volume)

The physical dimensions behind a needle gauge number: nominal outer diameter, inner diameter, wall thickness, and dead volume per 25.4 mm of needle. Gauge number alone is not enough to answer 'will this needle prime my 10 uL syringe' or 'what is the ID of a 26s needle' — the wall marker ('s', 'RW') changes the ID at the same gauge, and dead volume is what actually determines whether a small-volume syringe can be primed. Two independent publishers are cited and they agree where they overlap: Hamilton, a syringe maker, covers 34 gauge down to 10 gauge with dead volumes; New England Small Tube, a tube manufacturer, covers 6 to 27 gauge in regular wall with millimetre figures of its own. Each keeps its own naming, so the same needle can appear twice — as '18 gauge needle' and as '18 RW' — with a separate quote behind each.

Records51

Sources2

Verified2026-08-27

Review by2029-08-26

LicenceDimensional facts (a physical tolerance table) are not copyrightable; cited with attribution to the publishing vendor's technical reference page. No page content beyond the per-gauge figures is reproduced.

The data

Gauge number	Nominal O.D. (mm)	Nominal I.D. (mm)	Wall thickness (mm)	Dead volume (uL per 25.4 mm)
6 RW	5.15	4.39	.381
7 RW	4.57	3.81	.381
8 RW	4.19	3.43	.381
9 RW	3.76	3.00	.381
10 gauge needle	3.404	2.693	0.356	144.641 µL/25.4 mm
10 RW	3.40	2.69	.356
11 gauge needle	3.048	2.388	0.33	113.728 µL/25.4 mm
11 RW	3.05	2.39	.330
12 gauge needle	2.769	2.159	0.305	93 µL/25.4 mm
12 RW	2.77	2.16	.305
13 gauge needle	2.413	1.804	0.305	64.895 µL/25.4 mm
13 RW	2.41	1.80	.305
14 gauge needle	2.109	1.6	0.254	51.076 µL/25.4 mm
14 RW	2.11	1.60	.254
15 gauge needle	1.829	1.372	0.229	37.529 µL/25.4 mm
15 RW	1.83	1.37	.229
16 gauge needle	1.651	1.194	0.229	28.444 µL/25.4 mm
16 RW	1.65	1.19	.229
17 gauge needle	1.473	1.067	0.203	22.715 µL/25.4 mm
17 RW	1.47	1.07	.203
18 gauge needle	1.27	0.838	0.216	14.011 µL/25.4 mm
18 RW	1.27	0.84	.216
19 gauge needle	1.067	0.686	0.191	9.389 µL/25.4 mm
19 RW	1.07	0.69	.191
20 gauge needle	0.908	0.603	0.152	7.255 µL/25.4 mm
20 RW	0.91	0.61	.152
21 gauge needle	0.819	0.514	0.152	5.271 µL/25.4 mm
21 RW	0.81	0.51	.152
22 gauge needle	0.718	0.413	0.152	3.403 µL/25.4 mm
22 RW	0.71	0.41	.152
22s gauge needle	0.718	0.152	0.279
23 gauge needle	0.642	0.337	0.152	2.266 µL/25.4 mm
23 RW	0.64	0.33	.152
23s gauge needle	0.642	0.116	0.267	0.268 µL/25.4 mm
24 gauge needle	0.566	0.311	0.127	1.93 µL/25.4 mm
24 RW	0.56	0.31	.127
25 gauge needle	0.515	0.26	0.127	1.349 µL/25.4 mm
25 RW	0.51	0.25	.127
25s gauge needle	0.515	0.153	0.178	0.464 µL/25.4 mm
26 gauge needle	0.464	0.26	0.102	1.349 µL/25.4 mm
26 RW	0.46	0.25	.102
26s gauge needle	0.474	0.127	0.178	0.322 µL/25.4 mm
27 gauge needle	0.413	0.21	0.102	0.876 µL/25.4 mm
27 RW	0.41	0.20	.102
28 gauge needle	0.362	0.184	0.089	0.675 µL/25.4 mm
29 gauge needle	0.337	0.184	0.076	0.675 µL/25.4mm
30 gauge needle	0.312	0.159	0.076	0.504 µL/25.4 mm
31 gauge needle	0.261	0.133	0.064	0.353 µL/25.4 mm
32 gauge needle	0.235	0.108	0.064	0.233 µL/25.4 mm
33 gauge needle	0.21	0.108	0.051	0.233 µL/25.4 mm
34 gauge needle	0.159	0.051	0.051	0.052 µL/25.4 mm

Where this came from

Every record above links the page it was taken from and quotes the sentence that states it. These are the 2 sources this dataset was assembled from.

hamiltoncompany.comhttps://www.hamiltoncompany.com/laboratory-products/needles-knowledge/needle-gauge-chart
nesmalltube.comhttps://nesmalltube.com/wp-content/uploads/2025/06/Metric_Chart_Web.pdf

Machine-readable

data.jsonThe whole dataset — every record with its source URL and source quote.
Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
data.csvThe same records as one flat table, for a spreadsheet or a dataframe. The last four columns are the source URL, the quoted sentence it was read from, the date we last checked it, and which columns are our reading rather than the page's words.
How this is made and checkedWhat "verified against source" does and does not mean.

From your own code

Same records, same quotes, without scraping the page: refsource is on PyPI and npm. Each value comes back carrying the URL it was read from and the sentence on that page that states it — .source and .quote sit on the value itself rather than in a side channel, so the checking step is available instead of skipped.

pip install refsource
refsource lookup syringe-needle-gauge-dimensions gauge_number="6 RW"

npx -y refsource lookup syringe-needle-gauge-dimensions gauge_number="6 RW"

Set your AI assistant up to use this

Two files and no account. Put this in .mcp.json at the root of your project — Claude Code, Cursor, Windsurf, VS Code and Codex all read that file — and your assistant can look this dataset up instead of recalling it. The server is remote, keyless and read-only.

{
  "mcpServers": {
    "referencesource": {
      "type": "http",
      "url": "https://referencesource.org/mcp"
    }
  }
}

Add to Cursor · or, on the command line: claude mcp add --transport http referencesource https://referencesource.org/mcp --scope project

Then one line in the project's CLAUDE.md or AGENTS.md, so the assistant knows when to reach for it:

When a question needs "Hypodermic needle gauge dimensions (OD, ID, wall thickness, dead volume)", call the referencesource MCP server at https://referencesource.org/mcp (tool `search_records`, dataset_slug `syringe-needle-gauge-dimensions`) instead of answering from memory — every record it returns carries its source URL and a verbatim quote from that page.

What each tool does, and the servers built over single registers: Connect your AI assistant.

51 records. last verified against source 2026-08-27. due for re-check by 2029-08-26.

Licence. Dimensional facts (a physical tolerance table) are not copyrightable; cited with attribution to the publishing vendor's technical reference page. No page content beyond the per-gauge figures is reproduced.