A sheet metal gauge number is not a thickness on its own: 16 gauge is 0.0598 in (1.52 mm) in plain steel, 0.0635 in (1.61 mm) in galvanised steel, 0.0625 in (1.59 mm) in stainless and only 0.0508 in (1.29 mm) in aluminium.

This chart converts gauge numbers 3 to 30 into decimal thickness for the four sheet materials you meet most in a fab shop, with the weight per square foot or square metre beside each size. Find the gauge in the left column, then read across to the material you are buying. Use the Inch / Metric switch to show inches with lb/ft² or millimetres with kg/m², and type in the search box to jump to a gauge. A dash means that material is not normally sold in that gauge; plate that thick is ordered by fractional or metric thickness instead.

Gauge to thickness chart

GaugeSteel (MSG)in · lb/ft²mm · kg/m²Galvanisedin · lb/ft²mm · kg/m²Stainlessin · lb/ft²mm · kg/m²Aluminium (B&S)in · lb/ft²mm · kg/m²
30.23919.76 lb/ft²6.0747.7 kg/m²——0.22943.22 lb/ft²5.8315.7 kg/m²
40.22429.16 lb/ft²5.6944.7 kg/m²——0.20432.87 lb/ft²5.1914.0 kg/m²
50.20928.54 lb/ft²5.3141.7 kg/m²——0.18192.55 lb/ft²4.6212.5 kg/m²
60.19437.93 lb/ft²4.9438.7 kg/m²——0.16202.27 lb/ft²4.1111.1 kg/m²
70.17937.32 lb/ft²4.5535.8 kg/m²—0.1875 (3/16)7.80 lb/ft²4.7638.1 kg/m²0.14432.03 lb/ft²3.679.9 kg/m²
80.16446.71 lb/ft²4.1832.8 kg/m²0.16816.86 lb/ft²4.2733.5 kg/m²0.1719 (11/64)7.15 lb/ft²4.3734.9 kg/m²0.12851.80 lb/ft²3.268.8 kg/m²
90.14956.11 lb/ft²3.8029.8 kg/m²0.15326.26 lb/ft²3.8930.5 kg/m²0.1562 (5/32)6.50 lb/ft²3.9731.8 kg/m²0.11441.61 lb/ft²2.917.8 kg/m²
100.13455.49 lb/ft²3.4226.8 kg/m²0.13825.64 lb/ft²3.5127.6 kg/m²0.1406 (9/64)5.85 lb/ft²3.5728.6 kg/m²0.10191.43 lb/ft²2.597.0 kg/m²
110.11964.88 lb/ft²3.0423.8 kg/m²0.12335.04 lb/ft²3.1324.6 kg/m²0.1250 (1/8)5.20 lb/ft²3.1725.4 kg/m²0.09071.27 lb/ft²2.306.2 kg/m²
120.10464.27 lb/ft²2.6620.9 kg/m²0.10844.43 lb/ft²2.7521.6 kg/m²0.1094 (7/64)4.55 lb/ft²2.7822.2 kg/m²0.08081.13 lb/ft²2.055.5 kg/m²
130.08973.66 lb/ft²2.2817.9 kg/m²0.09343.81 lb/ft²2.3718.6 kg/m²0.0938 (3/32)3.90 lb/ft²2.3819.0 kg/m²0.07201.01 lb/ft²1.834.9 kg/m²
140.07473.05 lb/ft²1.9014.9 kg/m²0.07853.21 lb/ft²1.9915.7 kg/m²0.0781 (5/64)3.25 lb/ft²1.9815.9 kg/m²0.06410.90 lb/ft²1.634.4 kg/m²
150.06732.75 lb/ft²1.7113.4 kg/m²0.07102.90 lb/ft²1.8014.2 kg/m²0.0703 (9/128)2.93 lb/ft²1.7914.3 kg/m²0.05710.80 lb/ft²1.453.9 kg/m²
160.05982.44 lb/ft²1.5211.9 kg/m²0.06352.59 lb/ft²1.6112.7 kg/m²0.0625 (1/16)2.60 lb/ft²1.5912.7 kg/m²0.05080.71 lb/ft²1.293.5 kg/m²
170.05382.20 lb/ft²1.3710.7 kg/m²0.05752.35 lb/ft²1.4611.5 kg/m²0.0563 (9/160)2.34 lb/ft²1.4311.4 kg/m²0.04530.64 lb/ft²1.153.1 kg/m²
180.04781.95 lb/ft²1.219.5 kg/m²0.05162.11 lb/ft²1.3110.3 kg/m²0.0500 (1/20)2.08 lb/ft²1.2710.2 kg/m²0.04030.57 lb/ft²1.022.8 kg/m²
190.04181.71 lb/ft²1.068.3 kg/m²0.04561.86 lb/ft²1.169.1 kg/m²0.0437 (7/160)1.82 lb/ft²1.118.9 kg/m²0.03590.50 lb/ft²0.912.5 kg/m²
200.03591.47 lb/ft²0.917.2 kg/m²0.03961.62 lb/ft²1.017.9 kg/m²0.0375 (3/80)1.56 lb/ft²0.957.6 kg/m²0.03200.45 lb/ft²0.812.2 kg/m²
210.03291.34 lb/ft²0.846.6 kg/m²0.03661.49 lb/ft²0.937.3 kg/m²0.0344 (11/320)1.43 lb/ft²0.877.0 kg/m²0.02850.40 lb/ft²0.722.0 kg/m²
220.02991.22 lb/ft²0.766.0 kg/m²0.03361.37 lb/ft²0.856.7 kg/m²0.0312 (1/32)1.30 lb/ft²0.796.3 kg/m²0.02530.36 lb/ft²0.641.7 kg/m²
230.02691.10 lb/ft²0.685.4 kg/m²0.03061.25 lb/ft²0.786.1 kg/m²0.0281 (9/320)1.17 lb/ft²0.715.7 kg/m²0.02260.32 lb/ft²0.571.5 kg/m²
240.02390.98 lb/ft²0.614.8 kg/m²0.02761.13 lb/ft²0.705.5 kg/m²0.0250 (1/40)1.04 lb/ft²0.645.1 kg/m²0.02010.28 lb/ft²0.511.4 kg/m²
250.02090.85 lb/ft²0.534.2 kg/m²0.02471.01 lb/ft²0.634.9 kg/m²0.0219 (7/320)0.91 lb/ft²0.564.4 kg/m²0.01790.25 lb/ft²0.451.2 kg/m²
260.01790.73 lb/ft²0.453.6 kg/m²0.02170.89 lb/ft²0.554.3 kg/m²0.0187 (3/160)0.78 lb/ft²0.483.8 kg/m²0.01590.22 lb/ft²0.401.1 kg/m²
270.01640.67 lb/ft²0.423.3 kg/m²0.02020.82 lb/ft²0.514.0 kg/m²0.0172 (11/640)0.72 lb/ft²0.443.5 kg/m²0.01420.20 lb/ft²0.361.0 kg/m²
280.01490.61 lb/ft²0.383.0 kg/m²0.01870.76 lb/ft²0.473.7 kg/m²0.0156 (1/64)0.65 lb/ft²0.403.2 kg/m²0.01260.18 lb/ft²0.320.9 kg/m²
290.01350.55 lb/ft²0.342.7 kg/m²0.01720.70 lb/ft²0.443.4 kg/m²0.0141 (9/640)0.59 lb/ft²0.362.9 kg/m²0.01130.16 lb/ft²0.290.8 kg/m²
300.01200.49 lb/ft²0.302.4 kg/m²0.01570.64 lb/ft²0.403.1 kg/m²0.0125 (1/80)0.52 lb/ft²0.322.5 kg/m²0.01000.14 lb/ft²0.250.7 kg/m²

Steel: Manufacturers' Standard Gauge for sheet steel. Galvanised: galvanised sheet gauge (steel gauge plus 2.5 oz/ft² of coating). Stainless: US Standard Gauge (the fraction is shown in inch mode); some mills quote stainless in the steel MSG sizes instead. Aluminium: Brown & Sharpe / American Wire Gauge, d = 0.005 × 92(36−n)/39 in. Weights are calculated from thickness using 0.2836 lb/in³ (7.85 g/cm³) for steel and galvanised, 0.289 lb/in³ (8.00 g/cm³) for 304 stainless and 0.0975 lb/in³ (2.70 g/cm³) for 6061 aluminium, ignoring coating and rolling tolerance. Values are nominal; check critical sizes against the mill certificate, ASTM product standard or your supplier's table.

How to read the chart

Each cell shows the nominal thickness in bold type and the calculated weight underneath. In inch mode the stainless column also shows the fraction the gauge came from, for example 16 gauge stainless is 1/16 in.

Worked example. A drawing calls for "14 ga mild steel". Read across the 14 row: 0.0747 in (1.90 mm) and about 3.05 lb/ft². If the same part were made in 14 gauge aluminium it would be only 0.0641 in (1.63 mm) thick, which changes bend allowance, flat pattern size and stiffness. Ask which material and decimal thickness is meant before you cut.

For bending, put the decimal thickness, not the gauge, into the Sheet Metal Bend Calculator, and measure the actual sheet with a micrometer: rolled sheet can sit a few thousandths either side of nominal and that moves the bend deduction.

Why gauge numbers differ by material

There is no single gauge system. Sheet steel uses the Manufacturers' Standard Gauge, which was set from a weight per square foot (so each gauge is a fixed weight of steel rather than a round thickness). Galvanised sheet uses its own gauge that allows for the zinc coating, so it is about 0.0037 in thicker than plain steel at the same number. Stainless is commonly sold to the older US Standard Gauge, built from simple fractions of an inch. Aluminium, copper and brass use the Brown & Sharpe (American Wire Gauge) series, where every gauge step is a constant ratio of about 1.123 in thickness.

Outside North America most sheet is simply sold in millimetres (0.7, 0.9, 1.2, 1.5, 2.0, 3.0 mm and so on), and gauge numbers survive mainly as shop slang. That is why ordering by decimal thickness and grade is the safer habit: "1.5 mm 5251-H22" or "0.063 in 6061-T6" cannot be misread, while "16 gauge" can mean anything from 1.29 to 1.61 mm.

Sheet weight

Weight per area is just thickness times density. In inches, steel weighs about 40.8 lb per square foot for every inch of thickness; in metric, steel weighs 7.85 kg per square metre for every millimetre. Multiply by the sheet area to get the sheet weight.

Worked example. 10 ga steel = 0.1345 in × 40.84 = 5.49 lb/ft². A 4 × 8 ft sheet is 32 ft², so it weighs about 176 lb. In metric: 3.42 mm × 7.85 = 26.8 kg/m² × 2.97 m² ≈ 80 kg.

Catalogue gauge weights for steel can read about 2% higher than these figures because the Manufacturers' Standard Gauge was defined from a weight basis of 41.82 lb/ft² per inch. For shipping and lifting estimates either figure is close enough; for any other shape or material use the Weight & Volume Calculator.

Shop tips

  • Write the decimal on the drawing. Give thickness, grade and temper (for example 0.0598 in CR4 or 1.5 mm 304 2B), and use gauge only as a cross-check.
  • Measure before you program. Mic the sheet in a few places away from the edge and use the measured value for bend allowance and laser kerf settings.
  • Galvanised is thicker. The same gauge of galvanised steel is heavier and slightly thicker than plain steel, so do not swap the two in a press brake program without checking.
  • Aluminium is thinner and softer. 16 ga aluminium is about 15% thinner than 16 ga steel; size rivets and fasteners from the actual thickness (see the Pop Rivet Drill Size Guide).
  • Quoting laser or plasma work? Thickness drives cut speed and cost, so feed the decimal value into the DXF Cut Cost Estimator estimator.

Frequently asked questions

16 gauge plain steel is 0.0598 in (1.52 mm) under the Manufacturers' Standard Gauge. The same gauge number is 0.0635 in (1.61 mm) in galvanised steel, usually 0.0625 in (1.59 mm) in stainless and 0.0508 in (1.29 mm) in aluminium, so always check which material the gauge refers to.

No. Aluminium sheet is gauged on the Brown & Sharpe (AWG) scale, which is thinner than the steel scale at the same number. 16 gauge aluminium is 0.0508 in (1.29 mm), about 15% thinner than 16 gauge steel at 0.0598 in (1.52 mm).

Gauge numbers come from the old wire-drawing trade, where wire pulled through more dies got a higher number and a smaller diameter. Sheet steel gauges were later tied to a weight per square foot, but the number still goes up as the sheet gets thinner.

10 gauge steel is 0.1345 in (3.42 mm) thick and weighs about 5.49 lb per square foot (26.8 kg/m²), so a 4 x 8 ft sheet weighs about 176 lb (80 kg). Mill catalogues may list a slightly higher nominal figure of 5.625 lb/ft² because the gauge was defined from an older weight basis.

Order by decimal thickness (for example 0.060 in or 1.5 mm) plus the material grade, because the same gauge number means a different thickness in steel, galvanised, stainless and aluminium. Put the decimal size on drawings and purchase orders, and treat the gauge as a nickname.