18 gauge steel thickness calculator
In the Manufacturers Standard Gauge for steel, 18 gauge is 0.0478 in (1.214 mm). The gauge number counts down as the sheet gets thicker.
Where the neutral axis sits, as a fraction of thickness. 0.33 for tight bends, 0.5 for generous ones.
- Thickness in inches
- 0.047 80
- Weight of the sheet
- 19.062
- Weight per square metre
- 9.531 kg/m2
- Weight per square foot
- 0.8854 kg/ft2
- Minimum inside bend radius One thickness is a safe general rule for mild steel; check the alloy.
- 1.214
- Bend allowance
- 2.708
- Bend deduction
- 2.148
- Suggested V-die opening Eight times thickness is the usual air-bending starting point.
- 9.71
Show the working
- Sheet length = 2000
- Sheet width = 1000
- Steel density = 7850
- Bend angle = 90
- K-factor = 0.42
- Thickness = 1.21412 = 1.214 12
- Thickness in inches = 1.214 12 / 25.4 = 0.0478
- area_m2 = 2000 * 1000 / 1e6 = 2
- volume_m3 = 2 * 1.214 12 / 1000 = 0.002 428 24
- Weight of the sheet = 0.002 428 24 * 7850 = 19.0617
- Weight per square metre = 1.214 12 / 1000 * 7850 = 9.530 84
- Weight per square foot = 9.530 84 * 0.09290304 = 0.885 444
- Minimum inside bend radius = 1.214 12 * 1 = 1.214 12
- Bend allowance = rad(90) * (1.214 12 + 0.42 * 1.214 12) = 2.708 13
- Bend deduction = 2 * (1.214 12 + 1.214 12) * tan(rad(90)/2) - 2.708 13 = 2.148 35
- Suggested V-die opening = 1.214 12 * 8 = 9.712 96
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- weight = length x width x thickness x density
- bend allowance = angle in radians x (inside radius + K x thickness)
- bend deduction = 2 x (inside radius + thickness) x tan(angle/2) - bend allowance
Gauge numbers are not a single standard. Steel, aluminium, stainless and zinc all use different gauge tables for the same number, so always state the material.
The Manufacturers Standard Gauge descends from a weight-per-square-foot table, which is why the thicknesses are not a neat progression.
Frequently asked
How thick is 18 gauge steel?
0.0478 inches, or 1.214 mm, for uncoated sheet steel.
Is a higher gauge number thicker?
No. The gauge number counts down as thickness goes up, so 16 gauge is thicker than 20 gauge.
Where the numbers come from
- Thicknesses are the Manufacturers Standard Gauge for uncoated hot- and cold-rolled sheet steel.