Gauge numbers to inches, decimal, and millimeters — for steel, aluminum, and stainless steel. From Pro Form Metals in Reno, NV.
Gauge numbers can be confusing because they don't follow a universal standard — the same gauge number means different thicknesses depending on the material. Use the tabs below to switch between steel, aluminum, and stainless steel. Common fabrication gauges are highlighted.
| Gauge | Inches (Decimal) | Fraction (Approx.) | Millimeters | Common Use |
|---|---|---|---|---|
| 3 | 0.2391 | 15/64" | 6.07 mm | Heavy structural |
| 4 | 0.2242 | 7/32" | 5.69 mm | Heavy structural |
| 5 | 0.2092 | 13/64" | 5.31 mm | Structural plate |
| 6 | 0.1943 | 3/16" | 4.94 mm | Heavy plate |
| 7 | 0.1793 | 11/64" | 4.55 mm | Heavy plate |
| 8 | 0.1644 | 5/32" | 4.18 mm | Gates, heavy brackets |
| 9 | 0.1495 | 9/64" | 3.80 mm | Heavy sheet |
| 10 | 0.1345 | 9/64" | 3.42 mm | Railings, heavy fabrication |
| 11 | 0.1196 | 1/8" | 3.04 mm | Sheet metal work |
| 12 | 0.1046 | 7/64" | 2.66 mm | Fireplace surrounds, brackets |
| 13 | 0.0897 | 3/32" | 2.28 mm | General fabrication |
| 14 | 0.0747 | 5/64" | 1.90 mm | Roofing, siding, fascia |
| 15 | 0.0673 | 1/16" | 1.71 mm | General sheet |
| 16 | 0.0598 | 1/16" | 1.52 mm | Roofing panels, trim |
| 17 | 0.0538 | — | 1.37 mm | Light fabrication |
| 18 | 0.0478 | 3/64" | 1.21 mm | Chimney caps, kitchen hoods |
| 19 | 0.0418 | — | 1.06 mm | Light sheet |
| 20 | 0.0359 | 1/32" | 0.91 mm | Standing seam roofing |
| 21 | 0.0329 | — | 0.84 mm | Light panels |
| 22 | 0.0299 | — | 0.76 mm | Gutters, flashings, trim |
| 23 | 0.0269 | — | 0.68 mm | Light trim |
| 24 | 0.0239 | — | 0.61 mm | Standing seam, roofing trim |
| 25 | 0.0209 | — | 0.53 mm | Light applications |
| 26 | 0.0179 | — | 0.46 mm | Exposed fastener roofing |
| 27 | 0.0164 | — | 0.42 mm | Very light |
| 28 | 0.0149 | — | 0.38 mm | Flashings, valley, drip edge |
⚠️ Note: Steel uses the Manufacturers' Standard Gauge (MSG). Aluminum and brass use the Brown & Sharpe (B&S) gauge. For the same gauge number, these are different thicknesses — always verify material type before ordering. Highlighted rows are the most common gauges used in roofing, siding, and architectural fabrication.
Pro Form Metals fabricates roofing panels, trim, fascia, chimney caps, and custom architectural metalwork in Reno, NV — cut to spec, bent to profile, ready to install.
Get a Quote → (775) 742-6985Most standing seam metal roofing uses 24-gauge or 26-gauge steel. 24-gauge is heavier and more durable — preferred in snow country like the Sierra Nevada. 26-gauge is more economical for residential applications with moderate loads. Pro Form Metals typically fabricates roofing panels in 24 or 26 gauge depending on the project spec.
Metal fascia cladding and architectural trim typically runs 14 to 22 gauge depending on the application and desired rigidity. 16-gauge is a popular middle ground for fascia on commercial and high-end residential projects — stiff enough to hold a clean line, light enough to work with. See Pro Form's fascia cladding options.
Counterintuitively, lower gauge numbers mean thicker metal. 8-gauge steel is significantly thicker than 24-gauge. This trips up a lot of people — the gauge system evolved from wire drawing where more passes through the die produced a thinner (higher number) wire.
No. Steel and aluminum use different gauge standards (Manufacturers' Standard vs. Brown & Sharpe), so the same gauge number refers to different thicknesses. 16-gauge steel is 0.0598" while 16-gauge aluminum is 0.0508". Always specify both gauge and material when ordering.
Custom kitchen hoods and chimney caps are commonly fabricated in 18 or 20 gauge stainless steel, or 16–18 gauge carbon steel with appropriate coating. Heavier gauges (16 or lower) are used when structural rigidity matters, such as large commercial hoods or exterior chimney caps in high-wind areas. See Pro Form's custom range hoods or chimney cap fabrication.