Sheet steel in the United States is still specified by gauge, a number that runs opposite to thickness: the higher the gauge, the thinner the sheet. Because gauge is not a unit of measurement, the same gauge number means different thicknesses for standard carbon steel, galvanized steel, stainless and aluminum.
Use the charts below to convert steel gauge to decimal inches and weight per square foot.
Standard sheet steel gauge chart
Carbon steel sheet (hot-rolled and cold-rolled) follows the Manufacturers’ Standard Gauge. Weight is based on 41.82 lb per square foot per inch of thickness.
| Gauge | Inches | Weight (lb/sq ft) |
|---|---|---|
| 3 | 0.2391 | 10.000 |
| 4 | 0.2242 | 9.375 |
| 5 | 0.2092 | 8.750 |
| 6 | 0.1943 | 8.125 |
| 7 | 0.1793 | 7.500 |
| 8 | 0.1644 | 6.875 |
| 9 | 0.1495 | 6.250 |
| 10 | 0.1345 | 5.625 |
| 11 | 0.1196 | 5.000 |
| 12 | 0.1046 | 4.375 |
| 13 | 0.0897 | 3.750 |
| 14 | 0.0747 | 3.125 |
| 15 | 0.0673 | 2.812 |
| 16 | 0.0598 | 2.500 |
| 17 | 0.0538 | 2.250 |
| 18 | 0.0478 | 2.000 |
| 19 | 0.0418 | 1.750 |
| 20 | 0.0359 | 1.500 |
| 21 | 0.0329 | 1.375 |
| 22 | 0.0299 | 1.250 |
| 23 | 0.0269 | 1.125 |
| 24 | 0.0239 | 1.000 |
| 25 | 0.0209 | 0.875 |
| 26 | 0.0179 | 0.750 |
| 28 | 0.0149 | 0.625 |
| 30 | 0.0120 | 0.500 |
Galvanized steel gauge chart
Galvanized sheet gauge includes the zinc coating, so each gauge is slightly thicker (about 0.0037 in.) than the same gauge of uncoated steel.
| Gauge | Inches |
|---|---|
| 8 | 0.1681 |
| 9 | 0.1532 |
| 10 | 0.1382 |
| 11 | 0.1233 |
| 12 | 0.1084 |
| 13 | 0.0934 |
| 14 | 0.0785 |
| 15 | 0.0710 |
| 16 | 0.0635 |
| 17 | 0.0575 |
| 18 | 0.0516 |
| 19 | 0.0456 |
| 20 | 0.0396 |
| 21 | 0.0366 |
| 22 | 0.0336 |
| 23 | 0.0306 |
| 24 | 0.0276 |
| 25 | 0.0247 |
| 26 | 0.0217 |
| 28 | 0.0187 |
| 30 | 0.0157 |
Tips for specifying sheet thickness
- Call out decimal thickness on your drawings. Gauge numbers are nominal. Writing “0.120 in. (11 ga)” removes any doubt.
- Remember mill tolerances. Actual thickness varies within the tolerances of the governing ASTM specification, so design critical fits with that range in mind.
- Know where sheet ends and plate begins. Material thicker than about ¼ in. is usually ordered as plate by fractional inch rather than by gauge.
- Do not mix gauge systems. Stainless steel and aluminum use different gauge tables. When in doubt, call out the decimal thickness in inches.
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