Standard sheet metal gauge conversions for common engineering materials. Use gauge values as a quick reference and verify final material thickness from the applicable specification.
U.S. Standard Gauge
Common sheet metal gauge values for carbon and mild steel. Gauge numbers increase as sheet thickness decreases.
| Gauge | Thickness (in) | Thickness (mm) |
|---|---|---|
| 7 GA | 0.1793 | 4.554 |
| 8 GA | 0.1644 | 4.175 |
| 9 GA | 0.1495 | 3.797 |
| 10 GA | 0.1345 | 3.416 |
| 11 GA | 0.1196 | 3.038 |
| 12 GA | 0.1046 | 2.657 |
| 13 GA | 0.0897 | 2.281 |
| 14 GA | 0.0747 | 1.897 |
| 15 GA | 0.0673 | 1.709 |
| 16 GA | 0.0598 | 1.519 |
| 17 GA | 0.0538 | 1.367 |
| 18 GA | 0.0478 | 1.214 |
| 19 GA | 0.0418 | 1.067 |
| 20 GA | 0.0359 | 0.912 |
| 21 GA | 0.0329 | 0.836 |
| 22 GA | 0.0299 | 0.759 |
| 23 GA | 0.0269 | 0.683 |
| 24 GA | 0.0239 | 0.607 |
| 25 GA | 0.0209 | 0.531 |
| 26 GA | 0.0179 | 0.455 |
| 27 GA | 0.0164 | 0.417 |
| 28 GA | 0.0149 | 0.378 |
| 29 GA | 0.0135 | 0.343 |
| 30 GA | 0.0120 | 0.305 |
U.S. Standard Gauge
Common stainless steel sheet gauge values. Stainless steel uses a different gauge-to-thickness relationship than mild steel.
| Gauge | Thickness (in) | Thickness (mm) |
|---|---|---|
| 7 GA | 0.1875 | 4.762 |
| 8 GA | 0.1719 | 4.366 |
| 9 GA | 0.1563 | 3.969 |
| 10 GA | 0.1406 | 3.572 |
| 11 GA | 0.1250 | 3.175 |
| 12 GA | 0.1094 | 2.778 |
| 13 GA | 0.0940 | 2.388 |
| 14 GA | 0.0781 | 1.984 |
| 15 GA | 0.0703 | 1.588 |
| 16 GA | 0.0625 | 1.588 |
| 17 GA | 0.0562 | 1.427 |
| 18 GA | 0.0500 | 1.270 |
| 19 GA | 0.0437 | 1.109 |
| 20 GA | 0.0375 | 0.953 |
| 21 GA | 0.0344 | 0.874 |
| 22 GA | 0.0312 | 0.792 |
| 23 GA | 0.0281 | 0.714 |
| 24 GA | 0.0250 | 0.635 |
| 25 GA | 0.0219 | 0.556 |
| 26 GA | 0.0187 | 0.475 |
| 27 GA | 0.0172 | 0.437 |
| 28 GA | 0.0156 | 0.396 |
| 29 GA | 0.0141 | 0.358 |
| 30 GA | 0.0125 | 0.318 |
U.S. Standard Gauge
Common aluminum sheet gauge values. Aluminum gauge charts vary by alloy and product standard, so actual supplied thickness should be verified.
| Gauge | Thickness (in) | Thickness (mm) |
|---|---|---|
| 7 GA | 0.1443 | 3.665 |
| 8 GA | 0.1285 | 3.264 |
| 9 GA | 0.1144 | 2.906 |
| 10 GA | 0.1019 | 2.588 |
| 11 GA | 0.0907 | 2.303 |
| 12 GA | 0.0808 | 2.052 |
| 13 GA | 0.0720 | 1.829 |
| 14 GA | 0.0641 | 1.628 |
| 15 GA | 0.0571 | 1.450 |
| 16 GA | 0.0508 | 1.291 |
| 17 GA | 0.0453 | 1.151 |
| 18 GA | 0.0403 | 1.024 |
| 19 GA | 0.0359 | 0.912 |
| 20 GA | 0.0320 | 0.813 |
| 21 GA | 0.0285 | 0.724 |
| 22 GA | 0.0253 | 0.643 |
| 23 GA | 0.0226 | 0.574 |
| 24 GA | 0.0201 | 0.511 |
| 25 GA | 0.0179 | 0.455 |
| 26 GA | 0.0159 | 0.404 |
| 27 GA | 0.0142 | 0.361 |
| 28 GA | 0.0126 | 0.320 |
| 29 GA | 0.0113 | 0.287 |
| 30 GA | 0.0100 | 0.254 |
Gauge is a historical thickness designation rather than a direct dimensional unit. For the same gauge number, actual thickness can differ dramatically between steel, stainless steel, aluminum, and other materials.
For CAD modeling, fabrication drawings, and structural calculations, you should always explicitly state the nominal thickness in millimeters or inches rather than relying solely on the gauge number.