Sheet metal gauge conversion tables to inches and millimeters

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 / formatInchesmmProduct
22 Gauge0.0299″0.761008 cold-rolled
18 Gauge0.0478″1.211008 cold-rolled
16 Gauge0.0598″1.521008 cold-rolled
14 Gauge0.0747″1.901008 cold-rolled
12 Gauge0.1046″2.661008 cold-rolled
11 Gauge0.1196″3.041008 cold-rolled
10 Gauge0.1345″3.4244W hot-rolled
3/16″0.1875″4.7644W hot-rolled
1/4″0.250″6.3544W hot-rolled
5/16″0.3125″7.9444W hot-rolled
3/8″0.375″9.5344W hot-rolled
1/2″0.500″12.7044W 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 / formatInchesmm
24 Gauge0.025″0.64
22 Gauge0.0312″0.79
20 Gauge0.0375″0.95
18 Gauge0.050″1.27
16 Gauge0.0625″1.59
14 Gauge0.0781″1.98
12 Gauge0.1094″2.78
11 Gauge0.1250″3.18
7 Gauge0.1875″4.76
1/4″0.250″6.35
3/8″0.375″9.53
1/2″0.500″12.70

316 stainless

Gauge / formatInchesmm
24 Gauge0.025″0.64
22 Gauge0.031″0.79
20 Gauge0.038″0.97
18 Gauge0.050″1.27
16 Gauge0.063″1.60
14 Gauge0.078″1.98
12 Gauge0.109″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 / formatInchesmm
24 Gauge0.020″0.51
22 Gauge0.025″0.64
20 Gauge0.032″0.81
18 Gauge0.0403″1.02
14 Gauge0.0641″1.63
12 Gauge0.0808″2.05
11 Gauge0.0907″2.30
10 Gauge0.1019″2.59
8 Gauge0.1285″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

GaugeInchesmm
24 Gauge0.028″0.71
22 Gauge0.034″0.86
18 Gauge0.052″1.32
16 Gauge0.064″1.63
14 Gauge0.079″2.01
12 Gauge0.108″2.74

Galvanneal steel

GaugeInchesmm
22 Gauge0.034″0.86
18 Gauge0.052″1.32
16 Gauge0.064″1.63
14 Gauge0.079″2.01
12 Gauge0.108″2.74
11 Gauge0.123″3.12

How do you choose the right thickness for your part?

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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