Why does sheet metal gauge thickness change by material?

Gauge numbers come from material-specific standards. A 16 gauge carbon steel sheet is not the same thickness as 16 gauge aluminum or stainless steel.

Should I put gauge or decimal thickness on a drawing?

For production clarity, include the material and decimal thickness in inches or millimetres. Gauge can be useful shorthand, but decimal thickness avoids ambiguity.

Can FortiFab quote from gauge callouts?

Yes, but the fastest RFQs include material grade, thickness, finish, quantity, and drawing files. FortiFab will confirm available stock and fabrication fit before production.

Gauge thickness chart

Convert sheet metal gauge to inch and millimetre thickness

Gauge numbers vary by material. Use this chart to compare common carbon steel, galvanized steel, stainless steel, and aluminum thicknesses before preparing a FortiFab quote package.

Gauge to thickness reference

Gauge	Carbon steel	Galvanized steel	Stainless steel	Aluminum
10 ga	0.1345 in / 3.42 mm	0.1382 in / 3.51 mm	0.1406 in / 3.57 mm	0.1019 in / 2.59 mm
11 ga	0.1196 in / 3.04 mm	0.1233 in / 3.13 mm	0.1250 in / 3.17 mm	0.0907 in / 2.30 mm
12 ga	0.1046 in / 2.66 mm	0.1084 in / 2.75 mm	0.1094 in / 2.78 mm	0.0808 in / 2.05 mm
13 ga	0.0897 in / 2.28 mm	0.0934 in / 2.37 mm	0.0940 in / 2.39 mm	0.0720 in / 1.83 mm
14 ga	0.0747 in / 1.90 mm	0.0785 in / 1.99 mm	0.0781 in / 1.98 mm	0.0641 in / 1.63 mm
15 ga	0.0673 in / 1.71 mm	0.0710 in / 1.80 mm	0.0703 in / 1.79 mm	0.0571 in / 1.45 mm
16 ga	0.0598 in / 1.52 mm	0.0635 in / 1.61 mm	0.0625 in / 1.59 mm	0.0508 in / 1.29 mm
18 ga	0.0478 in / 1.21 mm	0.0516 in / 1.31 mm	0.0500 in / 1.27 mm	0.0403 in / 1.02 mm
20 ga	0.0359 in / 0.91 mm	0.0396 in / 1.01 mm	0.0375 in / 0.95 mm	0.0320 in / 0.81 mm
22 ga	0.0299 in / 0.76 mm	0.0336 in / 0.85 mm	0.0312 in / 0.79 mm	0.0253 in / 0.64 mm
24 ga	0.0239 in / 0.61 mm	0.0276 in / 0.70 mm	0.0250 in / 0.64 mm	0.0201 in / 0.51 mm
26 ga	0.0179 in / 0.45 mm	0.0217 in / 0.55 mm	0.0187 in / 0.47 mm	0.0159 in / 0.40 mm

Values are common reference thicknesses. Confirm actual stock, grade, coating, tolerance, and finish requirements before releasing a production drawing.

Best RFQ practice

Put the material, grade, decimal thickness, finish, and quantity on the drawing. Gauge-only callouts can be ambiguous across material types.

Related material guides

Carbon steel guide →Stainless steel guide →Aluminum guide →

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Sheet metal gauge FAQs

Use gauge references carefully: material-specific thicknesses matter for fit, forming, and quoting.