AWG Wire Gauge Calculator
Enter an AWG number (use 0 for 1/0, -1 for 2/0, -2 for 3/0 and -3 for 4/0) to get the exact diameter, area and resistance at 20 C. For learning and design checks, not safety certification.
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Formula
- Diameter:
d (mm) = 0.127 × 92^((36 − n) ÷ 39), with n = -3, -2, -1 for 4/0, 3/0, 2/0 - Area:
A = π ÷ 4 × d² - Resistance per metre:
R = ρ ÷ A, with copper ρ = 1.7241e-8 ohm m at 20 C - Per 1000 ft: multiply the per-metre value by 304.8
- Current guide:
A × 6 A/mm², general guidance only
Worked example
AWG 10: d = 0.127 × 92^(26 ÷ 39) = 2.588 mm (0.1019 in). Area is π ÷ 4 × 2.588² = 5.261 mm². Resistance is 1.7241e-8 ÷ 5.261e-6 = 0.003277 ohm/m, which is 0.9989 ohm per 1000 ft. The rough current guide is 5.261 × 6 = 31.6 A; treat it as guidance, not a rating.
Frequently asked questions
What is the AWG diameter formula?
d = 0.127 mm x 92^((36 - n)/39), where n is the gauge. For AWG 10 that is 0.127 x 92^(26/39) = 2.588 mm.
How is wire resistance worked out?
R = resistivity x length / area. Annealed copper at 20 C is 1.7241e-8 ohm m, so AWG 10 (5.261 mm2) is 0.003277 ohm per metre, or 0.9989 ohm per 1000 ft.
Does a smaller AWG number mean thicker wire?
Yes. Every 6 gauge steps roughly halves the diameter, and every 3 steps roughly halves the area. AWG 0 is 8.25 mm across, while AWG 36 is 0.127 mm.
How many amps can a wire carry?
The current guide here is general guidance only (about 6 A per mm2, so 31.6 A for AWG 10). Safe current depends on insulation, temperature, bundling and wiring rules, so use a code table; this is for learning and design checks, not safety certification.