| Gauge | Thickness (mm) | Thickness (inches) | Weight (kg/m²) |
|---|---|---|---|
| 7 | 4.554 | 0.1793 | 35.75 |
| 8 | 4.176 | 0.1644 | 32.78 |
| 9 | 3.797 | 0.1495 | 29.81 |
| 10 | 3.416 | 0.1345 | 26.81 |
| 11 | 3.038 | 0.1196 | 23.85 |
| 12 | 2.657 | 0.1046 | 20.86 |
| 13 | 2.278 | 0.0897 | 17.88 |
| 14 | 1.897 | 0.0747 | 14.89 |
| 15 | 1.709 | 0.0673 | 13.42 |
| 16 | 1.519 | 0.0598 | 11.92 |
| 17 | 1.367 | 0.0538 | 10.73 |
| 18 | 1.214 | 0.0478 | 9.53 |
| 19 | 1.062 | 0.0418 | 8.34 |
| 20 | 0.912 | 0.0359 | 7.16 |
| 21 | 0.836 | 0.0329 | 6.56 |
| 22 | 0.759 | 0.0299 | 5.96 |
| 23 | 0.683 | 0.0269 | 5.36 |
| 24 | 0.607 | 0.0239 | 4.76 |
| 25 | 0.531 | 0.0209 | 4.17 |
| 26 | 0.455 | 0.0179 | 3.57 |
| 27 | 0.417 | 0.0164 | 3.27 |
| 28 | 0.378 | 0.0149 | 2.97 |
| 29 | 0.343 | 0.0135 | 2.69 |
| 30 | 0.305 | 0.0120 | 2.39 |
The gauge system is a standardised way of specifying sheet metal thickness. In the standard steel gauge (MSG) system, gauge numbers range from 7 (thickest, ~4.554 mm) to 30 (thinnest, ~0.305 mm). The system is inversely proportional — higher gauge numbers indicate thinner material.
The most commonly used gauges in fabrication are 14 gauge (1.897 mm) for structural work, 18 gauge (1.214 mm) for general fabrication, and 22 gauge (0.759 mm) for HVAC and light enclosures. This converter covers the complete range from 7 to 30 gauge with weight per square metre calculated at mild steel density (7.85 g/cm³).
18 gauge sheet metal is 1.214 mm thick (0.0478 inches). It weighs approximately 9.53 kg per square metre in mild steel. 18 gauge is one of the most commonly used thicknesses for general fabrication and enclosures.
20 gauge sheet metal is 0.912 mm thick (0.0359 inches). It weighs approximately 7.16 kg per square metre in mild steel. 20 gauge is commonly used for light fabrication, HVAC ductwork, and decorative panels.
Sheet metal gauge is inversely related to thickness — a higher gauge number means thinner metal. For example, 10 gauge (3.416 mm) is much thicker than 24 gauge (0.607 mm). The gauge system originated from wire drawing: more draws (higher gauge) produced thinner wire.