---
type: chart
title: "Sheet Metal Gauge Chart"
tables: 5
url: https://manufacturingprocesses.org/charts/sheet-metal-gauge-chart
---

# Sheet Metal Gauge Chart

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

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.

## Carbon steel — Manufacturers' Standard Gauge (MSG)

| Gauge | Thickness (in) | Thickness (mm) |
| --- | --- | --- |
| 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 |

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

| Gauge | Thickness (in) | Thickness (mm) |
| --- | --- | --- |
| 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 |

## Stainless steel — US Standard Gauge (fraction-based)

| Gauge | Thickness (in) | Thickness (mm) |
| --- | --- | --- |
| 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 |

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

| Gauge | Thickness (in) | Thickness (mm) |
| --- | --- | --- |
| 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 |

## Mill thickness tolerance — cold-rolled steel sheet

| Gauge | Nominal (in) | Max (in) | Min (in) | Total band (in) |
| --- | --- | --- | --- | --- |
| 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 |

## Notes

**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.

## FAQ

### 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.

## Sources

- [Engineers Edge — Sheet Metal Wire Gauge Sizes Data Chart](https://www.engineersedge.com/gauge.htm)
- [Metal Supermarkets — Sheet Metal Gauge Chart](https://www.metalsupermarkets.com/sheet-metal-gauge-chart/)

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---

*Source: [Manufacturing Processes](https://manufacturingprocesses.org/charts/sheet-metal-gauge-chart)*

*Last updated: August 11, 2026*