Sheet Metal Gauge Chart
Gauge to thickness for the four metals tradespeople handle most, in inches with millimetres in brackets.
Quick answer
Higher gauge numbers are thinner metal. For uncoated steel: 10 ga = 0.1345 in, 12 ga = 0.1046 in, 14 ga = 0.0747 in, 16 ga = 0.0598 in, 18 ga = 0.0478 in, 20 ga = 0.0359 in. Aluminium at the same gauge number is thinner because it uses a different standard.
Gauge to thickness — inches (millimetres)
Steel follows the Manufacturers' Standard Gauge; galvanised adds the zinc coating; aluminium follows the Brown & Sharpe series.
| Gauge | Steel | Galvanised steel | Stainless steel | Aluminium |
|---|---|---|---|---|
| 3 ga | 0.2391 (6.073) | — | — | 0.2294 (5.827) |
| 4 ga | 0.2242 (5.695) | — | — | 0.2043 (5.189) |
| 5 ga | 0.2092 (5.314) | — | — | 0.1819 (4.620) |
| 6 ga | 0.1943 (4.935) | — | — | 0.1620 (4.115) |
| 7 ga | 0.1793 (4.554) | — | 0.1875 (4.762) | 0.1443 (3.665) |
| 8 ga | 0.1644 (4.176) | 0.1681 (4.270) | 0.1719 (4.366) | 0.1285 (3.264) |
| 9 ga | 0.1495 (3.797) | 0.1532 (3.891) | 0.1563 (3.970) | 0.1144 (2.906) |
| 10 ga | 0.1345 (3.416) | 0.1382 (3.510) | 0.1406 (3.571) | 0.1019 (2.588) |
| 11 ga | 0.1196 (3.038) | 0.1233 (3.132) | 0.1250 (3.175) | 0.0907 (2.304) |
| 12 ga | 0.1046 (2.657) | 0.1084 (2.753) | 0.1094 (2.779) | 0.0808 (2.052) |
| 13 ga | 0.0897 (2.278) | 0.0934 (2.372) | 0.0938 (2.383) | 0.0720 (1.829) |
| 14 ga | 0.0747 (1.897) | 0.0785 (1.994) | 0.0781 (1.984) | 0.0641 (1.628) |
| 15 ga | 0.0673 (1.709) | 0.0710 (1.803) | 0.0703 (1.786) | 0.0571 (1.450) |
| 16 ga | 0.0598 (1.519) | 0.0635 (1.613) | 0.0625 (1.588) | 0.0508 (1.290) |
| 17 ga | 0.0538 (1.367) | 0.0575 (1.461) | 0.0563 (1.430) | 0.0453 (1.151) |
| 18 ga | 0.0478 (1.214) | 0.0516 (1.311) | 0.0500 (1.270) | 0.0403 (1.024) |
| 19 ga | 0.0418 (1.062) | 0.0456 (1.158) | 0.0438 (1.113) | 0.0359 (0.912) |
| 20 ga | 0.0359 (0.912) | 0.0396 (1.006) | 0.0375 (0.952) | 0.0320 (0.813) |
| 21 ga | 0.0329 (0.836) | 0.0366 (0.930) | 0.0344 (0.874) | 0.0285 (0.724) |
| 22 ga | 0.0299 (0.759) | 0.0336 (0.853) | 0.0313 (0.795) | 0.0253 (0.643) |
| 23 ga | 0.0269 (0.683) | 0.0306 (0.777) | 0.0281 (0.714) | 0.0226 (0.574) |
| 24 ga | 0.0239 (0.607) | 0.0276 (0.701) | 0.0250 (0.635) | 0.0201 (0.511) |
| 25 ga | 0.0209 (0.531) | 0.0247 (0.627) | 0.0219 (0.556) | 0.0179 (0.455) |
| 26 ga | 0.0179 (0.455) | 0.0217 (0.551) | 0.0188 (0.478) | 0.0159 (0.404) |
| 27 ga | 0.0164 (0.417) | 0.0202 (0.513) | 0.0172 (0.437) | 0.0142 (0.361) |
| 28 ga | 0.0149 (0.378) | 0.0187 (0.475) | 0.0156 (0.396) | 0.0126 (0.320) |
| 29 ga | 0.0135 (0.343) | 0.0172 (0.437) | 0.0141 (0.358) | 0.0113 (0.287) |
| 30 ga | 0.0120 (0.305) | 0.0157 (0.399) | 0.0125 (0.318) | 0.0100 (0.254) |
Published standard — source: Manufacturers' Standard Gauge for steel; Brown & Sharpe for aluminium
Source & method: Millimetre values are exact conversions at 25.4 mm per inch. Mill tolerances of several thousandths are normal on any sheet product.
Common uses by gauge
| Gauge | Steel thickness | Typical use |
|---|---|---|
| 7 ga | 0.1793 in (4.55 mm) | Structural plate, heavy brackets |
| 10 ga | 0.1345 in (3.42 mm) | Heavy machine guards, truck bodies |
| 12 ga | 0.1046 in (2.66 mm) | Industrial enclosures, shelving |
| 14 ga | 0.0747 in (1.90 mm) | Outdoor enclosures, strut and framing |
| 16 ga | 0.0598 in (1.52 mm) | General-purpose electrical enclosures |
| 18 ga | 0.0478 in (1.21 mm) | Ductwork, box covers, trim |
| 20 ga | 0.0359 in (0.91 mm) | Light ductwork, flashing |
| 22 ga | 0.0299 in (0.76 mm) | Register boots, light fabrication |
| 24 ga | 0.0239 in (0.61 mm) | Roof flashing, light ducting |
| 26 ga | 0.0179 in (0.46 mm) | Residential ductwork, light sheet |
Frequently asked
- How thick is 16 gauge sheet metal?
- 16 gauge uncoated steel is 0.0598 inches (1.519 mm). Galvanised 16 gauge is slightly thicker at 0.0635 inches because of the zinc coating, stainless is 0.0625 inches, and 16 gauge aluminium is 0.0508 inches.
- Does a higher gauge number mean thicker metal?
- No. Higher gauge numbers are thinner material. 14 gauge steel is thicker than 20 gauge. The scale is inverted, the same as wire gauge.
- Why does gauge thickness differ between metals?
- Each metal uses its own gauge standard. Steel follows the Manufacturers' Standard Gauge, which is weight-based, while aluminium follows the Brown & Sharpe series. The same gauge number therefore gives different thicknesses.
- What gauge is used for electrical enclosures?
- General-purpose indoor enclosures are commonly 16 gauge steel; heavier industrial and outdoor enclosures use 14 or 12 gauge. Junction box covers and trim are often 18 or 20 gauge.
- How do I convert sheet metal gauge to millimetres?
- Look up the thickness in inches for the specific metal, then multiply by 25.4. This chart lists both columns so no conversion is needed.
Gauge measuring and cutting tools
Gauge measuring and cutting tools
Verify thickness in the field.
- Sheet metal gauge wheelCheck gauge in the field against this chart.Check price on Amazon →
- Digital caliperMeasure thickness directly in inches or mm.Check price on Amazon →
- Aviation snips setLeft, right and straight cut for sheet work.Check price on Amazon →
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