18 gauge aluminium thickness
18 gauge aluminium is 0.0403 in (1.02 mm) thick, per the Brown & Sharpe (AWG) gauge. The same gauge number means a different thickness in other metals: steel 0.0478 in, galvanized steel 0.0516 in, stainless steel 0.0500 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 | 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 (this page) | Brown & Sharpe (AWG) gauge | 0.0403 | 1.02 | 2.74 |
| Gauge | Thickness (in) | Thickness (mm) | kg/m² | lb/ft² |
|---|---|---|---|---|
| 12 ga | 0.0808 | 2.05 | 5.50 | 1.13 |
| 14 ga | 0.0641 | 1.63 | 4.36 | 0.89 |
| 16 ga | 0.0508 | 1.29 | 3.46 | 0.71 |
| 18 ga (this page) | 0.0403 | 1.02 | 2.74 | 0.56 |
| 20 ga | 0.0320 | 0.81 | 2.18 | 0.45 |
| 22 ga | 0.0253 | 0.64 | 1.72 | 0.35 |
| 24 ga | 0.0201 | 0.51 | 1.37 | 0.28 |
Practical notes
Gauge is a convention, not a unit: a higher gauge number is thinner, and steps are not even. 18 gauge is 0.0403 in for aluminium (aluminum) sheet, but steel 0.0478 in, galvanized steel 0.0516 in and stainless steel 0.0500 in. Put the decimal thickness on drawings and purchase orders to avoid mix-ups.
Aluminium sheet is usually ordered by decimal thickness (e.g. 0.063 in, 1.6 mm) rather than gauge. Measure with a micrometer before calculating bend allowances or press-fit clearances.
Weight per area here is thickness × density (5052 aluminium, 2.68 g/cm³): 1.02 mm × 2.68 = 2.74 kg/m². Multiply by the sheet area for blank weight; a 4 × 8 ft sheet is 2.973 m², so about 8.2 kg (18.0 lb).
Aluminium uses the Brown & Sharpe scale, the same numbers as AWG wire, which runs thinner than steel gauges at the same number.
FAQ
How thick is 18 gauge aluminium?
0.0403 in, which is 1.02 mm, per the Brown & Sharpe (AWG) gauge.
How thick is 18 gauge in mm?
For aluminium, 18 gauge is 1.02 mm. In other metals: steel 1.21 mm, galvanized steel 1.31 mm, stainless steel 1.27 mm.
How much does 18 gauge aluminium weigh?
About 2.74 kg per square metre (0.56 lb per square foot), using 5052 aluminium, 2.68 g/cm³.
Is 18 gauge thicker than 16 gauge?
No. Higher gauge numbers are thinner: 16 ga aluminium is 0.0508 in, 18 ga is 0.0403 in.
Sources: Aluminium: Brown & Sharpe (AWG) gauge · Densities: EN 10025 / ASTM A1008 (steel), ASTM A240 (stainless), Aluminum Association (5052) · 1 in = 25.4 mm (exact)
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