Sheet metal gauge chart
Gauge numbers mean different thicknesses in different systems: 16 gauge is 1.63mm in the UK (SWG) but 1.52mm for US steel and 1.29mm for aluminium. Here are all five side by side, in millimetres, with the weight of each steel gauge.
Gauge to millimetres
Thickness in mm. The higher the gauge, the thinner the sheet. Merchants usually sell by the nearest round size: UK 16 gauge is sold as 1.6mm, 18 gauge as 1.2mm, so order in millimetres when you can.
| Gauge | UK SWG | US steel | US galvanised | US stainless | Aluminium |
|---|---|---|---|---|---|
| 3 | 6.40 | 6.07 (0.2391″) | – | 6.35 | 5.83 |
| 4 | 5.89 | 5.69 (0.2242″) | – | 5.95 | 5.19 |
| 5 | 5.38 | 5.31 (0.2092″) | – | 5.56 | 4.62 |
| 6 | 4.88 | 4.93 (0.1943″) | – | 5.16 | 4.12 |
| 7 | 4.47 | 4.56 (0.1793″) | – | 4.76 | 3.66 |
| 8 | 4.06 | 4.18 (0.1644″) | 4.27 | 4.37 | 3.26 |
| 9 | 3.66 | 3.80 (0.1495″) | 3.89 | 3.97 | 2.91 |
| 10 | 3.25 | 3.42 (0.1345″) | 3.51 | 3.57 | 2.59 |
| 11 | 2.95 | 3.04 (0.1196″) | 3.13 | 3.17 | 2.30 |
| 12 | 2.64 | 2.66 (0.1046″) | 2.75 | 2.78 | 2.05 |
| 13 | 2.34 | 2.28 (0.0897″) | 2.37 | 2.38 | 1.83 |
| 14 | 2.03 | 1.90 (0.0747″) | 1.99 | 1.98 | 1.63 |
| 15 | 1.83 | 1.71 (0.0673″) | 1.80 | 1.79 | 1.45 |
| 16 | 1.63 | 1.52 (0.0598″) | 1.61 | 1.59 | 1.29 |
| 17 | 1.42 | 1.37 (0.0538″) | 1.46 | 1.43 | 1.15 |
| 18 | 1.22 | 1.21 (0.0478″) | 1.31 | 1.27 | 1.02 |
| 19 | 1.02 | 1.06 (0.0418″) | 1.16 | 1.11 | 0.91 |
| 20 | 0.91 | 0.91 (0.0359″) | 1.01 | 0.95 | 0.81 |
| 21 | 0.81 | 0.84 (0.0329″) | 0.93 | 0.87 | 0.72 |
| 22 | 0.71 | 0.76 (0.0299″) | 0.85 | 0.79 | 0.64 |
| 23 | 0.61 | 0.68 (0.0269″) | 0.78 | 0.71 | 0.57 |
| 24 | 0.56 | 0.61 (0.0239″) | 0.70 | 0.64 | 0.51 |
| 25 | 0.51 | 0.53 (0.0209″) | 0.63 | 0.56 | 0.45 |
| 26 | 0.46 | 0.46 (0.0179″) | 0.55 | 0.48 | 0.40 |
| 27 | 0.42 | 0.42 (0.0164″) | 0.51 | 0.44 | 0.36 |
| 28 | 0.38 | 0.38 (0.0149″) | 0.47 | 0.40 | 0.32 |
| 29 | 0.35 | 0.34 (0.0135″) | 0.44 | 0.36 | 0.29 |
| 30 | 0.31 | 0.30 (0.0120″) | 0.40 | 0.32 | 0.25 |
UK SWG: Imperial Standard Wire Gauge (BS 3737). US steel: Manufacturers’ Standard Gauge, defined by weight (thickness = lb per sq ft ÷ 41.82); galvanised adds the zinc coating. US stainless: US Standard Gauge (1893). Aluminium: Brown & Sharpe (American Wire Gauge). Sheet is rolled to a tolerance, so a real sheet can be a few hundredths of a millimetre either side.
Weight of steel sheet by gauge
Mild steel at 7,850kg/m³: 7.85kg per square metre for every millimetre of thickness. US steel gauges are defined by weight, so their pounds per square foot are exact.
| Gauge | UK SWG, kg/m² | UK SWG, 2500×1250 sheet (kg) | US steel, kg/m² | US steel, per sq ft |
|---|---|---|---|---|
| 8 | 31.90 | 99.7 | 32.78 | 6.875 lb |
| 9 | 28.71 | 89.7 | 29.80 | 6.25 lb |
| 10 | 25.52 | 79.8 | 26.82 | 5.625 lb |
| 11 | 23.13 | 72.3 | 23.84 | 5 lb |
| 12 | 20.74 | 64.8 | 20.86 | 4.375 lb |
| 13 | 18.34 | 57.3 | 17.88 | 3.75 lb |
| 14 | 15.95 | 49.8 | 14.90 | 3.125 lb |
| 15 | 14.36 | 44.9 | 13.41 | 2.8125 lb |
| 16 | 12.76 | 39.9 | 11.92 | 2.5 lb |
| 17 | 11.17 | 34.9 | 10.73 | 2.25 lb |
| 18 | 9.57 | 29.9 | 9.54 | 2 lb |
| 19 | 7.98 | 24.9 | 8.34 | 1.75 lb |
| 20 | 7.18 | 22.4 | 7.15 | 1.5 lb |
| 21 | 6.38 | 19.9 | 6.56 | 1.375 lb |
| 22 | 5.58 | 17.4 | 5.96 | 1.25 lb |
| 23 | 4.79 | 15.0 | 5.36 | 1.125 lb |
| 24 | 4.39 | 13.7 | 4.77 | 1 lb |
| 25 | 3.99 | 12.5 | 4.17 | 0.875 lb |
| 26 | 3.59 | 11.2 | 3.58 | 0.75 lb |
Stainless is about 1% heavier than mild steel, aluminium about a third of the weight. For any size, shape or metal, use the metal weight calculator.
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