Sheet metal gauge chart: gauge to inches and mm for steel, galvanized, stainless and aluminum

Sheet metal is ordered by gauge, 16, 14 or 10 gauge, and drawn in inches or millimetres. The gauge is a number, not a size, and the same number gives a different thickness in each material. This chart gives every gauge in inches and millimetres for carbon steel, galvanized, stainless and aluminum, and what a square foot and a square metre of steel weigh.

For the weight of a whole sheet or a cut part, the calculator is in the steel plate weight guide; for the thickness inside a bend calculation, in bend allowance and K-factor.

Sheet metal gauge chart

Steel is the Manufacturers' Standard Gauge (MSG) for uncoated carbon steel. Galvanized has its own gauge, measured over the zinc; stainless follows the older U.S. Standard Gauge; and aluminum is the Brown & Sharpe gauge, a different scale altogether.

Mills and service centres publish nominal thicknesses that differ from the chart by a thousandth or two, and the rolling tolerance is wider than that. To cut and to weigh, use the thickness measured with callipers or a micrometer.

Steel sheet weight by gauge

Weight per square foot and per square metre of carbon steel, at 0.2836 lb/in³ (7.85 kg/dm³), the density the weight calculator uses. A 4 × 8 ft sheet is 32 ft².

The MSG was defined by weight, 41.82 lb/ft² for every inch of thickness, so mill charts list 16 gauge at 2.5 lb/ft² and 10 gauge at 5.625. At the 0.2836 lb/in³ of carbon steel the same sheets weigh about 2% less, which is what a scale reads.

Why a higher gauge is a thinner sheet

The numbers come from wire drawing, where the gauge counted the passes through the draw plate: more passes, thinner wire. Sheet inherited the order, and each gauge became a row in a table. There is no formula from the number to the thickness.

Both American sheet gauges fix the weight per square foot of each number, not the thickness. The U.S. Standard Gauge of 1893 assumed wrought iron; the Manufacturers' Standard Gauge that replaced it for steel assumes steel, which is heavier. Both put 16 gauge at 2.5 lb/ft², which is why the older gauge is thicker: 0.0625 in against 0.0598 in.

Gauge in a flat pattern

Every Planichapa pattern is laid out on the neutral axis, at mid-thickness. A 12 in OD cylinder in 16 gauge opens to π × (12 − 0.0598) = 37.51 in, 3/16 in shorter than the outside circumference. The thickness field of every part offers the gauges of steel, galvanized, stainless and aluminum, with the thickness of this chart.

In a press brake bend, the thickness sets the deduction at each fold: the bent profile and the bend allowance and K-factor guide do the arithmetic.

Frequently asked questions

How thick is 16 gauge steel?

0.0598 in, or 1.519 mm, in uncoated carbon steel. 16 gauge galvanized is 0.0635 in (1.613 mm), stainless 0.0625 in (1.588 mm) and aluminum 0.0508 in (1.290 mm).

How thick is 14 gauge steel?

0.0747 in, or 1.897 mm. It weighs 3.05 lb per square foot, 14.89 kg per square metre.

How thick is 20 gauge steel?

0.0359 in, or 0.912 mm, and it weighs 1.47 lb per square foot. 20 gauge galvanized is 0.0396 in (1.006 mm).

How thick is 10 gauge?

0.1345 in (3.416 mm) in steel, just over 1/8 in. 10 gauge aluminum is much thinner, 0.1019 in (2.588 mm), because aluminum follows another scale.

What gauge is 1/8 inch?

In steel, 11 gauge, 0.1196 in (3.038 mm), is the nearest. In stainless, 11 gauge is exactly 1/8 in, 0.125 in.

What gauge is 3/16 inch?

7 gauge steel is 0.1793 in (4.554 mm), a little under 3/16 in (0.1875). Past 7 gauge, plate is ordered by the fraction: 3/16, 1/4, 3/8 in.

Is a higher gauge thicker?

No: the higher the gauge, the thinner the sheet. 10 gauge steel is 0.1345 in and 20 gauge is 0.0359 in.