18 gauge galvanized steel thickness
18 gauge galvanized steel is 0.0516 in (1.31 mm) thick, per the galvanized sheet gauge. The same gauge number means a different thickness in other metals: steel 0.0478 in, stainless steel 0.0500 in, aluminium 0.0403 in.
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| Material | Gauge standard | Thickness (in) | Thickness (mm) | kg/m² |
|---|---|---|---|---|
| Steel | Manufacturers' Standard Gauge | 0.0478 | 1.21 | 9.53 |
| Galvanized steel (this page) | galvanized sheet gauge | 0.0516 | 1.31 | 10.29 |
| Stainless steel | U.S. Standard Gauge (stainless sheet chart) | 0.0500 | 1.27 | 10.07 |
| Aluminium | Brown & Sharpe (AWG) gauge | 0.0403 | 1.02 | 2.74 |
| Gauge | Thickness (in) | Thickness (mm) | kg/m² | lb/ft² |
|---|---|---|---|---|
| 12 ga | 0.1084 | 2.75 | 21.61 | 4.43 |
| 14 ga | 0.0785 | 1.99 | 15.65 | 3.21 |
| 16 ga | 0.0635 | 1.61 | 12.66 | 2.59 |
| 18 ga (this page) | 0.0516 | 1.31 | 10.29 | 2.11 |
| 20 ga | 0.0396 | 1.01 | 7.90 | 1.62 |
| 22 ga | 0.0336 | 0.85 | 6.70 | 1.37 |
| 24 ga | 0.0276 | 0.70 | 5.50 | 1.13 |
Practical notes
Gauge is a convention, not a unit: a higher gauge number is thinner, and steps are not even. 18 gauge is 0.0516 in for hot-dip galvanized steel sheet (thickness includes the zinc coating), but steel 0.0478 in, stainless steel 0.0500 in and aluminium 0.0403 in. Put the decimal thickness on drawings and purchase orders to avoid mix-ups.
Mills supply sheet to a thickness tolerance (ASTM A568 / A480 / EN 10131), so a measured sheet can be a few thousandths of an inch off the nominal value. Measure with a micrometer before calculating bend allowances or press-fit clearances.
Weight per area here is thickness × density (steel, 7.85 g/cm³, applied to the coated thickness): 1.31 mm × 7.85 = 10.29 kg/m². Multiply by the sheet area for blank weight; a 4 × 8 ft sheet is 2.973 m², so about 30.6 kg (67.4 lb).
Galvanized gauge thickness includes the zinc layer, which is why 18 ga galvanized (0.0516 in) is thicker than uncoated 18 ga steel (0.0478 in).
FAQ
How thick is 18 gauge galvanized steel?
0.0516 in, which is 1.31 mm, per the galvanized sheet gauge.
How thick is 18 gauge in mm?
For galvanized steel, 18 gauge is 1.31 mm. In other metals: steel 1.21 mm, stainless steel 1.27 mm, aluminium 1.02 mm.
How much does 18 gauge galvanized steel weigh?
About 10.29 kg per square metre (2.11 lb per square foot), using steel, 7.85 g/cm³, applied to the coated thickness.
Is 18 gauge thicker than 16 gauge?
No. Higher gauge numbers are thinner: 16 ga galvanized steel is 0.0635 in, 18 ga is 0.0516 in.
Sources: Galvanized steel: galvanized sheet gauge · Densities: EN 10025 / ASTM A1008 (steel), ASTM A240 (stainless), Aluminum Association (5052) · 1 in = 25.4 mm (exact)
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