Sheet Metal Gauge Chart: Thickness in Inches and mm

Sheet metal gauge works like wire gauge: the higher the number, the thinner the metal. The catch is that each metal has its own scale. A sheet of 16 gauge steel, 16 gauge galvanized and 16 gauge aluminum are three different thicknesses, so the gauge on its own isn’t enough to order or match a piece.

Sheet metal gauge chart

Gauge	Steel	Galvanized steel	Stainless steel	Aluminum
8	0.1644 in (4.18 mm)	0.1681 in (4.27 mm)	0.1719 in (4.37 mm)	0.1285 in (3.26 mm)
10	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	0.1196 in (3.04 mm)	0.1233 in (3.13 mm)	0.1250 in (3.18 mm)	0.0907 in (2.30 mm)
12	0.1046 in (2.66 mm)	0.1084 in (2.75 mm)	0.1094 in (2.78 mm)	0.0808 in (2.05 mm)
14	0.0747 in (1.90 mm)	0.0785 in (1.99 mm)	0.0781 in (1.98 mm)	0.0641 in (1.63 mm)
16	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	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	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	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	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	0.0179 in (0.46 mm)	0.0217 in (0.55 mm)	0.0187 in (0.47 mm)	0.0159 in (0.40 mm)
28	0.0149 in (0.38 mm)	0.0187 in (0.47 mm)	0.0156 in (0.40 mm)	0.0126 in (0.32 mm)
30	0.0120 in (0.30 mm)	0.0157 in (0.40 mm)	0.0125 in (0.32 mm)	0.0100 in (0.25 mm)

Steel uses the Manufacturers’ Standard Gauge; galvanized steel is the same base sheet plus its zinc coating, so it’s always a little thicker. Aluminum, copper and brass use the Brown & Sharpe scale, the same numbers as AWG wire gauge. Real sheets vary slightly within mill tolerances.

Which gauge for which job

Gauge (steel)	Typical uses
10–11	Trailer beds, heavy brackets, truck parts
12–14	Heavy-duty shelving, tool boxes, structural brackets
16	Car body patch panels, workbench tops, steel studs (heavy)
18–20	Car body panels, appliance cases, metal roofing trim
22–24	Large HVAC trunk ducts, roofing panels, flashing
26–30	Small HVAC ducts, light flashing, crafts

Metal from about 3/16 inch (0.1875 in) and thicker is usually called plate and is sold by its fractional thickness instead of a gauge.

How to measure sheet metal thickness

1. Calipers or a micrometer give the most accurate reading. Measure away from the cut edge, where burrs make it look thicker.
2. A sheet metal gauge tool (a disk with labeled slots) shows the gauge directly; find the narrowest slot the sheet slides into.
3. Without either, stack 10 identical scraps and measure the stack with a mm ruler, then divide by 10.

Then match your measurement to the right column: a 1.6 mm sheet is 16 gauge if it’s galvanized, but about 14 gauge if it’s aluminum. To convert, use mm to inches or inches to mm.

More DIY charts: wire gauge · screw and bolt sizes · drill bit sizes · rebar sizes.