Sheet Metal Gauge Chart

Name: Sheet Metal Gauge Chart
Creator: Manufacturing Processes

Gauge-to-thickness conversions for steel, galvanized steel, stainless and aluminum, gauges 3 to 30, in inches and millimeters — plus the mill tolerance band.

Tables: 5
Rows: 114
Units: in, mm
References: 2
Revised: 2026-08-11

Carbon steel — Manufacturers' Standard Gauge (MSG)

28 rows

Gauge	Thicknessin	Thicknessmm
3	0.2391	6.073
4	0.2242	5.695
5	0.2092	5.314
6	0.1943	4.935
7	0.1793	4.554
8	0.1644	4.176
9	0.1495	3.797
10	0.1345	3.416
11	0.1196	3.038
12	0.1046	2.657
13	0.0897	2.278
14	0.0747	1.897
15	0.0673	1.709
16	0.0598	1.519
17	0.0538	1.367
18	0.0478	1.214
19	0.0418	1.062
20	0.0359	0.912
21	0.0329	0.836
22	0.0299	0.759
23	0.0269	0.683
24	0.0239	0.607
25	0.0209	0.531
26	0.0179	0.455
27	0.0164	0.417
28	0.0149	0.378
29	0.0135	0.343
30	0.012	0.305
No rows match that filter.

28 rows × 3 columnsUnits: in, mm

Basis and references

Read before use

Sheet metal gauge is not a unit. It is an index into a table, and there are four different tables in daily use: carbon steel follows the Manufacturers' Standard Gauge (MSG), which is weight-derived — 16 ga is 2.5 lb/ft². Galvanized sheet uses the steel MSG value plus 0.0037 in for the zinc coating. Stainless follows the fraction-based US Standard Gauge, in exact 1/64 in steps from gauge 3 to 14 and 1/128 in steps from 15 to 30. Aluminum, brass and copper follow the Brown & Sharpe (AWG) geometric series, ratio 92^(1/39) per step.

The result is that one gauge number means four different thicknesses. 18 ga steel is 0.0478 in, 18 ga galvanized is 0.0516 in, 18 ga stainless is 0.0500 in and 18 ga aluminum is 0.0403 in — a 28% spread. In every standard, a larger gauge number means thinner material.

Millimeter columns here are computed at exactly 25.4 mm/in and rounded to three decimals, not transcribed, so they carry none of the rounding errors that circulate in published charts.

References

Every value on this page was set against at least two of these sources and recomputed rather than transcribed. Where they disagree, the disagreement is recorded in the notes below.

Galvanized steel — Galvanized Sheet Gauge (steel MSG + 0.0037 in)

23 rows

Gauge	Thicknessin	Thicknessmm
8	0.1681	4.27
9	0.1532	3.891
10	0.1382	3.51
11	0.1233	3.132
12	0.1084	2.753
13	0.0934	2.372
14	0.0785	1.994
15	0.071	1.803
16	0.0635	1.613
17	0.0575	1.46
18	0.0516	1.311
19	0.0456	1.158
20	0.0396	1.006
21	0.0366	0.93
22	0.0336	0.853
23	0.0306	0.777
24	0.0276	0.701
25	0.0247	0.627
26	0.0217	0.551
27	0.0202	0.513
28	0.0187	0.475
29	0.0172	0.437
30	0.0157	0.399
No rows match that filter.

23 rows × 3 columnsUnits: in, mm

Stainless steel — US Standard Gauge (fraction-based)

24 rows

Gauge	Thicknessin	Thicknessmm
7	0.1875	4.762
8	0.1719	4.366
9	0.1563	3.97
10	0.1406	3.571
11	0.125	3.175
12	0.1094	2.779
13	0.0938	2.383
14	0.0781	1.984
15	0.0703	1.786
16	0.0625	1.587
17	0.0563	1.43
18	0.05	1.27
19	0.0438	1.113
20	0.0375	0.952
21	0.0344	0.874
22	0.0313	0.795
23	0.0281	0.714
24	0.025	0.635
25	0.0219	0.556
26	0.0188	0.478
27	0.0172	0.437
28	0.0156	0.396
29	0.0141	0.358
30	0.0125	0.318
No rows match that filter.

24 rows × 3 columnsUnits: in, mm

Aluminum, brass and copper — Brown & Sharpe (AWG)

28 rows

Gauge	Thicknessin	Thicknessmm
3	0.2294	5.827
4	0.2043	5.189
5	0.1819	4.62
6	0.162	4.115
7	0.1443	3.665
8	0.1285	3.264
9	0.1144	2.906
10	0.1019	2.588
11	0.0907	2.304
12	0.0808	2.052
13	0.072	1.829
14	0.0641	1.628
15	0.0571	1.45
16	0.0508	1.29
17	0.0453	1.151
18	0.0403	1.024
19	0.0359	0.912
20	0.032	0.813
21	0.0285	0.724
22	0.0253	0.643
23	0.0226	0.574
24	0.0201	0.511
25	0.0179	0.455
26	0.0159	0.404
27	0.0142	0.361
28	0.0126	0.32
29	0.0113	0.287
30	0.01	0.254
No rows match that filter.

28 rows × 3 columnsUnits: in, mm

Mill thickness tolerance — cold-rolled steel sheet

11 rows

Gauge	Nominalin	Maxin	Minin	Total bandin
10	0.1345	0.1405	0.1285	0.012
11	0.1196	0.1256	0.1136	0.012
12	0.1046	0.1106	0.0986	0.012
14	0.0747	0.0797	0.0697	0.01
16	0.0598	0.0648	0.0548	0.01
18	0.0478	0.0518	0.0438	0.008
20	0.0359	0.0389	0.0329	0.006
22	0.0299	0.0329	0.0269	0.006
24	0.0239	0.0269	0.0209	0.006
26	0.0179	0.0199	0.0159	0.004
28	0.0149	0.0169	0.0129	0.004
No rows match that filter.

11 rows × 5 columnsUnits: in

Revision and twin

2026-08-11

Last reviewed 2026-08-11. This page carries 114 rows across 5 tables, all of them in the HTML — nothing is paginated, gated or fetched.

Plain-Markdown twin: /charts/sheet-metal-gauge-chart.md

Notes to the tables

4 notes

Where this data disagrees with itself, with other published charts, or with what the number looks like it means.

Dimension in decimals, not in gauge. The mill tolerance band on cold-rolled steel sheet is frequently wider than the step between adjacent gauges: 16 ga is nominally 0.0598 in but ships anywhere from 0.0548 to 0.0648 in, a 0.010 in band, while the gap from 16 ga to 15 ga is only 0.0075 in. A drawing that reads "16 GA" without naming the alloy can legitimately be built to three different thicknesses.
Aluminum values published by Engineers Edge contain errors. Its second aluminum table lists gauge 26 as 0.017 in; the Brown & Sharpe series and Metal Supermarkets both give 0.01594 in, which rounds to 0.016. Gauges 17, 21 and 23 are also rounded to 2–3 decimals in that table (0.045, 0.028 and 0.023 against the exact 0.0453, 0.0285 and 0.0226). This chart uses the exact Brown & Sharpe series throughout.
Stainless gauges 3–6 and galvanized gauges 3–7 are genuinely absent, not missing. Neither source lists them: stainless in that thickness is sold as plate in fractional sizes, and the galvanized gauge series starts at 8.
Internal check on the galvanized column: every galvanized value equals the steel MSG value plus 0.0037 in to within 0.0001 in across all 23 gauges, which independently corroborates both source charts.

Questions

6 questions

How thick is 16 gauge steel?

16 gauge carbon steel is 0.0598 in (1.519 mm) under the Manufacturers' Standard Gauge. The same gauge number is 0.0635 in in galvanized steel, 0.0625 in in stainless and 0.0508 in in aluminum, so the material has to be stated alongside the gauge.

Is 16 gauge thicker than 18 gauge?

Yes. Gauge numbers run backwards: the larger the number, the thinner the sheet. 16 ga steel is 0.0598 in and 18 ga steel is 0.0478 in, so 16 ga is about 25% thicker.

Why is aluminum gauge different from steel gauge?

They come from unrelated standards. Steel sheet uses the Manufacturers' Standard Gauge, which was derived from weight per square foot, while aluminum follows the Brown & Sharpe wire gauge, a geometric series with a ratio of 92^(1/39) per step. The numbering coincides but the thicknesses do not.

Why is galvanized sheet thicker than plain steel at the same gauge?

The galvanized gauge series adds a fixed 0.0037 in allowance for the zinc coating on top of the steel MSG value. A 16 ga galvanized sheet is 0.0635 in against 0.0598 in for 16 ga plain steel.

Should I specify gauge or thickness on a drawing?

Specify thickness with units. Gauge is ambiguous across material families, and on cold-rolled steel the mill tolerance band — 0.010 in at 16 gauge — is wider than the step to the next gauge, so the gauge number alone does not pin the thickness down.

What is the thinnest gauge in these tables?

Gauge 30, which is 0.0120 in (0.305 mm) in steel, 0.0157 in galvanized, 0.0125 in stainless and 0.0100 in aluminum.

How to cite this page

Manufacturing Processes. “Sheet Metal Gauge Chart.” manufacturingprocesses.org, last reviewed 2026-08-11. https://manufacturingprocesses.org/charts/sheet-metal-gauge-chart

If you reproduce a table, cite the standard it derives from as well — the references are the primary sources, this page is a cross-checked transcription of them.