Sheet metal gauges
16 gauge is 1.519 mm in steel, 1.613 mm galvanised, 1.588 mm in stainless and 1.290 mm in aluminium. Each metal kept its own gauge system, so the number alone does not give the thickness. Choose the gauge and the metal for the thickness in millimetres and inches and the mass of a square metre, or enter a thickness for the nearest gauge.
- Thickness t
- In inches
- Mass per m²
- Gauge system
- Manufacturers' Standard Gauge
How it’s calculated
Steel: the 1893 law’s weight per square foot for the gauge over 41.82 lb/ft² per inch. Galvanised: the same with 2.5 oz/ft² of zinc added. Stainless: the 1893 gauge’s decimal-inch thickness. Aluminium: the Brown & Sharpe wire gauge, 0.005 × 92^((36 − n)/39) in. Millimetres = inches × 25.4; mass per m² = t (mm) × density (g/cm³).
Gauge to thickness, mm (in)
| Gauge | Steel | Galvanised | Stainless | Aluminium |
|---|---|---|---|---|
| 7 | 4.554 (0.1793) | – | 4.763 (0.1875) | 3.665 (0.1443) |
| 8 | 4.176 (0.1644) | 4.270 (0.1681) | 4.366 (0.1719) | 3.264 (0.1285) |
| 9 | 3.797 (0.1495) | 3.891 (0.1532) | 3.970 (0.1563) | 2.906 (0.1144) |
| 10 | 3.416 (0.1345) | 3.510 (0.1382) | 3.571 (0.1406) | 2.588 (0.1019) |
| 11 | 3.038 (0.1196) | 3.132 (0.1233) | 3.175 (0.1250) | 2.304 (0.0907) |
| 12 | 2.657 (0.1046) | 2.753 (0.1084) | 2.779 (0.1094) | 2.052 (0.0808) |
| 13 | 2.278 (0.0897) | 2.372 (0.0934) | 2.383 (0.0938) | 1.829 (0.0720) |
| 14 | 1.897 (0.0747) | 1.994 (0.0785) | 1.984 (0.0781) | 1.628 (0.0641) |
| 15 | 1.709 (0.0673) | 1.803 (0.0710) | 1.786 (0.0703) | 1.450 (0.0571) |
| 16 | 1.519 (0.0598) | 1.613 (0.0635) | 1.588 (0.0625) | 1.290 (0.0508) |
| 17 | 1.367 (0.0538) | 1.461 (0.0575) | 1.430 (0.0563) | 1.151 (0.0453) |
| 18 | 1.214 (0.0478) | 1.311 (0.0516) | 1.270 (0.0500) | 1.024 (0.0403) |
| 19 | 1.062 (0.0418) | 1.158 (0.0456) | 1.113 (0.0438) | 0.912 (0.0359) |
| 20 | 0.912 (0.0359) | 1.006 (0.0396) | 0.953 (0.0375) | 0.813 (0.0320) |
| 21 | 0.836 (0.0329) | 0.930 (0.0366) | 0.874 (0.0344) | 0.724 (0.0285) |
| 22 | 0.759 (0.0299) | 0.853 (0.0336) | 0.795 (0.0313) | 0.643 (0.0253) |
| 23 | 0.683 (0.0269) | 0.777 (0.0306) | 0.714 (0.0281) | 0.574 (0.0226) |
| 24 | 0.607 (0.0239) | 0.701 (0.0276) | 0.635 (0.0250) | 0.511 (0.0201) |
| 25 | 0.531 (0.0209) | 0.627 (0.0247) | 0.556 (0.0219) | 0.455 (0.0179) |
| 26 | 0.455 (0.0179) | 0.551 (0.0217) | 0.478 (0.0188) | 0.404 (0.0159) |
| 27 | 0.417 (0.0164) | 0.513 (0.0202) | 0.437 (0.0172) | 0.361 (0.0142) |
| 28 | 0.378 (0.0149) | 0.475 (0.0187) | 0.396 (0.0156) | 0.320 (0.0126) |
| 29 | 0.343 (0.0135) | 0.437 (0.0172) | 0.358 (0.0141) | 0.287 (0.0113) |
| 30 | 0.305 (0.0120) | 0.399 (0.0157) | 0.318 (0.0125) | 0.254 (0.0100) |
Why does a larger gauge number mean thinner sheet?
Gauges began as counts: the number of draws through a die for wire, and for sheet steel a weight per square foot set by an 1893 US law. Each step down the scale is a lighter, thinner sheet, so the number rises as the sheet thins. Steel’s gauge is still worked out from that weight, galvanised sheet adds the zinc’s weight, stainless kept the law’s decimal-inch thicknesses, and aluminium uses the wire gauge. When it matters, order sheet by its thickness in millimetres.