12 gauge steel thickness
12 gauge steel is 0.1046 in (2.66 mm) thick, per the Manufacturers' Standard Gauge. The same gauge number means a different thickness in other metals: galvanized steel 0.1084 in, stainless steel 0.1094 in, aluminium 0.0808 in.
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| Material | Gauge standard | Thickness (in) | Thickness (mm) | kg/m² |
|---|---|---|---|---|
| Steel (this page) | Manufacturers' Standard Gauge | 0.1046 | 2.66 | 20.86 |
| Galvanized steel | galvanized sheet gauge | 0.1084 | 2.75 | 21.61 |
| Stainless steel | U.S. Standard Gauge (stainless sheet chart) | 0.1094 | 2.78 | 22.04 |
| Aluminium | Brown & Sharpe (AWG) gauge | 0.0808 | 2.05 | 5.50 |
| Gauge | Thickness (in) | Thickness (mm) | kg/m² | lb/ft² |
|---|---|---|---|---|
| 8 ga | 0.1644 | 4.18 | 32.78 | 6.71 |
| 10 ga | 0.1345 | 3.42 | 26.82 | 5.49 |
| 11 ga | 0.1196 | 3.04 | 23.85 | 4.88 |
| 12 ga (this page) | 0.1046 | 2.66 | 20.86 | 4.27 |
| 14 ga | 0.0747 | 1.90 | 14.89 | 3.05 |
| 16 ga | 0.0598 | 1.52 | 11.92 | 2.44 |
| 18 ga | 0.0478 | 1.21 | 9.53 | 1.95 |
Practical notes
Gauge is a convention, not a unit: a higher gauge number is thinner, and steps are not even. 12 gauge is 0.1046 in for uncoated carbon steel (cold-rolled / hot-rolled sheet), but galvanized steel 0.1084 in, stainless steel 0.1094 in and aluminium 0.0808 in. Put the decimal thickness on drawings and purchase orders to avoid mix-ups.
Mills supply sheet to a thickness tolerance (ASTM A568 / A480 / EN 10131), so a measured sheet can be a few thousandths of an inch off the nominal value. Measure with a micrometer before calculating bend allowances or press-fit clearances.
Weight per area here is thickness × density (carbon steel, 7.85 g/cm³): 2.66 mm × 7.85 = 20.86 kg/m². Multiply by the sheet area for blank weight; a 4 × 8 ft sheet is 2.973 m², so about 62.0 kg (136.7 lb).
Manufacturers' Standard Gauge is based on a steel weight of 41.82 lb/ft² per inch of thickness, which is why its decimal values look irregular.
FAQ
How thick is 12 gauge steel?
0.1046 in, which is 2.66 mm, per the Manufacturers' Standard Gauge.
How thick is 12 gauge in mm?
For steel, 12 gauge is 2.66 mm. In other metals: galvanized steel 2.75 mm, stainless steel 2.78 mm, aluminium 2.05 mm.
How much does 12 gauge steel weigh?
About 20.86 kg per square metre (4.27 lb per square foot), using carbon steel, 7.85 g/cm³.
Is 12 gauge thicker than 11 gauge?
No. Higher gauge numbers are thinner: 11 ga steel is 0.1196 in, 12 ga is 0.1046 in.
Sources: Steel: Manufacturers' Standard Gauge · Densities: EN 10025 / ASTM A1008 (steel), ASTM A240 (stainless), Aluminum Association (5052) · 1 in = 25.4 mm (exact)
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