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Sheet Metal Gauge Chart

Convert sheet metal gauge numbers to thickness in inches and millimeters for steel, aluminum, and stainless steel.
Mild Steel
GaugeInchesMM
70.17934.55
80.16444.18
90.14953.80
100.13453.42
110.11963.04
120.10462.66
140.07471.90
160.05981.52
180.04781.21
200.03590.91
220.02990.76
240.02390.61
260.01790.45
280.01490.38
Aluminum
GaugeInchesMM
70.14433.67
80.12853.26
90.11442.91
100.10192.59
110.09072.31
120.08082.05
140.06411.63
160.05081.29
180.04031.02
200.03200.81
220.02540.64
240.02010.51
260.01590.41
280.01260.32
Stainless Steel
GaugeInchesMM
70.18744.76
80.17194.37
90.15633.97
100.14063.57
110.12503.18
120.10942.78
140.07811.98
160.06251.59
180.05001.27
200.03750.95
220.03130.79
240.02500.64
260.01880.48
280.01560.40

Sheet Metal Gauge Thickness by Material

Gauge numbers do not convert to the same thickness for every metal. Use these charts to compare mild steel, aluminum, and stainless steel thicknesses in both inches and millimeters before choosing material for a fabricated part.

Gauge Is Not Universal

The same gauge number can mean different thicknesses depending on whether the material is steel, aluminum, or stainless steel.

Lower Gauge Means Thicker Metal

Sheet metal gauge runs opposite of normal numeric sizing: 10 gauge is thicker than 16 gauge, and 16 gauge is thicker than 20 gauge.

Use Inches and Millimeters

Decimal thickness is the safest value for quoting, CAD, tolerance checks, and comparing material options across suppliers.

Learn more about gauge thickness: What is Sheet Metal Gauge?

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