Sheet Metal Gauge Chart: Steel, Stainless & Aluminum
A gauge number is not a universal thickness. Choose the material before using the lookup: the same number can describe three different nominal sheet thicknesses.
Calculate and check
Default values are examples. Replace them with verified inputs for your job. Changing a unit or mode does not convert existing inputs.
| Gauge | Steel (in) | Stainless (in) | Aluminum (in) |
|---|---|---|---|
| 10 | 0.1345 | 0.14062 | 0.1019 |
| 12 | 0.1046 | 0.10937 | 0.08081 |
| 14 | 0.0747 | 0.07812 | 0.06408 |
| 16 | 0.0598 | 0.0625 | 0.05082 |
| 18 | 0.0478 | 0.05 | 0.0403 |
| 20 | 0.0359 | 0.0375 | 0.03196 |
| 22 | 0.0299 | 0.03125 | 0.02535 |
| 24 | 0.0239 | 0.025 | 0.0201 |
Convert the thickness, not the gauge number
The interactive lookup multiplies the selected inch value by 25.4 to obtain millimeters. It does not use a linear gauge formula or interpolate an unlisted gauge. For 18 gauge, the table gives steel 0.0478 in, stainless 0.0500 in and aluminum 0.04030 in. The corresponding values are 1.21412, 1.27000 and 1.02362 mm.
A drawing calling for 1.2 mm steel and a purchase order calling for 18 gauge may not specify exactly the same nominal stock. Confirm the ordered thickness range and material specification rather than silently treating the labels as identical.
How to use this table in fabrication
Use a measured or specified thickness for bend calculations, fit clearances and mass estimates. Coatings and product tolerances can affect the delivered dimensions. The listed steel column is not a galvanized-sheet table, and none of these columns represents electrical wire AWG.
For a mixed-material assembly, specify millimeters or inches on the drawing in addition to any gauge designation. Record alloy, temper or grade, finish and thickness tolerance on the purchasing documents. If the desired gauge is outside this selected range, consult the supplier’s complete chart rather than extending the sequence.
Why an apparently small difference matters
A fixed thickness difference changes sheet mass in direct proportion to thickness. It can also affect tooling choice and the inside geometry of a formed assembly. Two panels sold under the same gauge number are therefore not automatically interchangeable across materials. The lookup is a nominal reference, not an incoming-inspection acceptance limit.
Expanded selected-gauge table: inches and millimeters
The interactive selector above retains eight even-number gauges. This static reference adds selected odd gauges and extends the published range. These are the Metal Supermarkets nominal mild-steel, stainless-steel and aluminum sheet values, not galvanized-sheet values, wire AWG requirements, or a thickness-tolerance standard. An unlisted gauge has not been interpolated.
| Gauge | Mild steel in | Mild steel mm | Stainless in | Stainless mm | Aluminum in | Aluminum mm |
|---|---|---|---|---|---|---|
| 7 | 0.1793 | 4.5542 | — | — | 0.1443 | 3.6652 |
| 8 | 0.1644 | 4.1758 | 0.17187 | 4.3655 | 0.1285 | 3.2639 |
| 9 | 0.1495 | 3.7973 | 0.15625 | 3.9688 | 0.1144 | 2.9058 |
| 10 | 0.1345 | 3.4163 | 0.14062 | 3.5717 | 0.1019 | 2.5883 |
| 11 | 0.1196 | 3.0378 | 0.125 | 3.1750 | 0.09074 | 2.3048 |
| 12 | 0.1046 | 2.6568 | 0.10937 | 2.7780 | 0.08081 | 2.0526 |
| 14 | 0.0747 | 1.8974 | 0.07812 | 1.9842 | 0.06408 | 1.6276 |
| 16 | 0.0598 | 1.5189 | 0.0625 | 1.5875 | 0.05082 | 1.2908 |
| 18 | 0.0478 | 1.2141 | 0.050 | 1.2700 | 0.04030 | 1.0236 |
| 20 | 0.0359 | 0.9119 | 0.0375 | 0.9525 | 0.03196 | 0.8118 |
| 22 | 0.0299 | 0.7595 | 0.03125 | 0.7938 | 0.02535 | 0.6439 |
| 24 | 0.0239 | 0.6071 | 0.025 | 0.6350 | 0.02010 | 0.5105 |
| 26 | 0.0179 | 0.4547 | 0.01875 | 0.4763 | 0.01594 | 0.4049 |
| 28 | 0.0149 | 0.3785 | 0.01562 | 0.3967 | 0.01264 | 0.3211 |
| 30 | — | — | 0.0125 | 0.3175 | 0.01003 | 0.2548 |
A dash means that the source’s selected table did not give that material/gauge combination; it does not prove the product cannot exist. Displayed precision is a unit conversion, not a guaranteed manufacturing tolerance.
Turn a lookup into an unambiguous order
For 11-gauge mild steel, 0.1196 × 25.4 = 3.03784 mm. For 11-gauge stainless, 0.125 × 25.4 = 3.175 mm. The difference is 0.13716 mm, even though both are called 11 gauge. Specify the material grade, nominal physical thickness, permitted thickness range and finish on the purchase order. Confirm which gauge convention the supplier uses.
Use specified or measured thickness in the bend calculator and sheet-weight calculator. Coating thickness and delivered tolerances cannot be inferred from the gauge label alone.
Content updated October 8, 2026. Sources and numerical examples are explained above; examples are not production test results. Editorial method · Report a correction.
References and verification
Original explanations and worked examples by MfgWorkbench. Sources below support the stated concepts or selected reference data; they do not certify every example or a production application.
For a correction, send the page URL, the affected value and supporting documentation through our contact page.