Gauge / inch / mm conversion table
Why isn't gauge the same from one metal to another?
"Gauge" is a holdover from old rolling standards, and each metal family has its own: steel follows a scale based on the weight of the steel sheet, galvanized steel a scale adjusted for the zinc coating, stainless and aluminum yet other scales. As a result, the same gauge number does not give the same thickness from one material to another.
That's the classic trap: 16G in mild steel is 0.0598″ (1.52 mm), 16G in 304 stainless is 0.0625″ (1.59 mm) and 16G in galvanized steel is 0.064″ (1.63 mm). As for 5052 aluminum, it simply isn't offered in 16G at Laseo — its 14G (0.0641″) is the closest. If your assembly depends on a precise thickness, always rely on inches or millimeters, never on the gauge number alone.
Note: the thicknesses below are those of the sheets actually in stock at Laseo — they may differ slightly from theoretical conversion tables. Millimeters are converted from inches (× 25.4) and rounded to two decimals. In the application, each material displays its exact thickness in inches anyway: impossible to get it wrong.
Mild steel
Two products depending on thickness: from 22G to 11G, a 1008 cold-rolled steel; from 10G up, a 44W hot-rolled steel. Details on the mild steel data sheet.
| Gauge / format | Inches | mm | Product |
|---|---|---|---|
| 22 Gauge | 0.0299″ | 0.76 | 1008 cold-rolled |
| 18 Gauge | 0.0478″ | 1.21 | 1008 cold-rolled |
| 16 Gauge | 0.0598″ | 1.52 | 1008 cold-rolled |
| 14 Gauge | 0.0747″ | 1.90 | 1008 cold-rolled |
| 12 Gauge | 0.1046″ | 2.66 | 1008 cold-rolled |
| 11 Gauge | 0.1196″ | 3.04 | 1008 cold-rolled |
| 10 Gauge | 0.1345″ | 3.42 | 44W hot-rolled |
| 3/16″ | 0.1875″ | 4.76 | 44W hot-rolled |
| 1/4″ | 0.250″ | 6.35 | 44W hot-rolled |
| 5/16″ | 0.3125″ | 7.94 | 44W hot-rolled |
| 3/8″ | 0.375″ | 9.53 | 44W hot-rolled |
| 1/2″ | 0.500″ | 12.70 | 44W hot-rolled |
304 and 316 stainless steel
Both alloys follow the same gauge scale; the 304 is offered up to 1/2″, the 316 up to 1/8″.
304 stainless
| Gauge / format | Inches | mm |
|---|---|---|
| 24 Gauge | 0.025″ | 0.64 |
| 22 Gauge | 0.0312″ | 0.79 |
| 20 Gauge | 0.0375″ | 0.95 |
| 18 Gauge | 0.050″ | 1.27 |
| 16 Gauge | 0.0625″ | 1.59 |
| 14 Gauge | 0.0781″ | 1.98 |
| 12 Gauge | 0.1094″ | 2.78 |
| 11 Gauge | 0.1250″ | 3.18 |
| 7 Gauge | 0.1875″ | 4.76 |
| 1/4″ | 0.250″ | 6.35 |
| 3/8″ | 0.375″ | 9.53 |
| 1/2″ | 0.500″ | 12.70 |
316 stainless
| Gauge / format | Inches | mm |
|---|---|---|
| 24 Gauge | 0.025″ | 0.64 |
| 22 Gauge | 0.031″ | 0.79 |
| 20 Gauge | 0.038″ | 0.97 |
| 18 Gauge | 0.050″ | 1.27 |
| 16 Gauge | 0.063″ | 1.60 |
| 14 Gauge | 0.078″ | 1.98 |
| 12 Gauge | 0.109″ | 2.77 |
| 1/8″ | 0.125″ | 3.18 |
5052-H32 aluminum
The aluminum gauge scale gives noticeably thinner sheets than steel at the same number — 18G aluminum is 0.0403″ versus 0.0478″ for mild steel. Details on the 5052-H32 aluminum data sheet.
| Gauge / format | Inches | mm |
|---|---|---|
| 24 Gauge | 0.020″ | 0.51 |
| 22 Gauge | 0.025″ | 0.64 |
| 20 Gauge | 0.032″ | 0.81 |
| 18 Gauge | 0.0403″ | 1.02 |
| 14 Gauge | 0.0641″ | 1.63 |
| 12 Gauge | 0.0808″ | 2.05 |
| 11 Gauge | 0.0907″ | 2.30 |
| 10 Gauge | 0.1019″ | 2.59 |
| 8 Gauge | 0.1285″ | 3.26 |
| 3/16″ | 0.1875″ | 4.76 |
| 1/4″ | 0.250″ | 6.35 |
| 3/8″ | 0.375″ | 9.53 |
| 1/2″ | 0.500″ | 12.70 |
G90 galvanized steel and galvanneal steel
The zinc coating adds to the base steel, which shifts the scale slightly: 16G galvanized is 0.064″ versus 0.0598″ for bare mild steel. The G90 galvanized and the galvanneal steel share the same thicknesses on their common gauges.
G90 galvanized
| Gauge | Inches | mm |
|---|---|---|
| 24 Gauge | 0.028″ | 0.71 |
| 22 Gauge | 0.034″ | 0.86 |
| 18 Gauge | 0.052″ | 1.32 |
| 16 Gauge | 0.064″ | 1.63 |
| 14 Gauge | 0.079″ | 2.01 |
| 12 Gauge | 0.108″ | 2.74 |
Galvanneal steel
| Gauge | Inches | mm |
|---|---|---|
| 22 Gauge | 0.034″ | 0.86 |
| 18 Gauge | 0.052″ | 1.32 |
| 16 Gauge | 0.064″ | 1.63 |
| 14 Gauge | 0.079″ | 2.01 |
| 12 Gauge | 0.108″ | 2.74 |
| 11 Gauge | 0.123″ | 3.12 |
How do you choose the right thickness for your part?
- Replacing an existing part? Measure it with calipers and take the closest thickness in inches within the right metal's family — not the same gauge number in a different metal.
- Your drawing is in millimeters? Find the closest mm value in the tables; the application displays the exact thickness in inches when you pick the material.
- Will the part be bent? Thickness affects the bend radius, the minimum flange and the flat pattern — check the bending guide before finalizing.
- Small holes or fine details? The minimums (hole, bridge, edge distance) increase with thickness — see our kerf, tolerances and minimum holes page.
Unsure which thickness to choose for your application? Write to us at info@laseo.ca — we'll reply before you prepare your quote.
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