Wire Gauge Calculator
AWG specs: diameter, resistance, and ampacity.
AWG Gauge
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Diameter (mm)
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Diameter (inches)
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Area (mm²)
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Area (kcmil)
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Resistance (Ω/km)
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Resistance (Ω/1000ft)
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Ampacity (Copper)
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Ampacity (Aluminum)
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Common Wire Gauge Reference
| AWG | Diam (mm) | Area (mm²) | Ω/km | Cu Amps | Al Amps |
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Frequently Asked Questions
How is AWG wire diameter calculated? +
AWG uses a logarithmic scale. The diameter in inches is calculated as 0.005 x 92^((36-n)/39), where n is the AWG number. Each 6-gauge increase roughly doubles the diameter.
What determines a wire's ampacity rating? +
Ampacity depends on wire material (copper vs aluminum), insulation type, ambient temperature, and how many conductors are bundled together. The values shown are typical ratings for copper in free air at 30C.
When should I use aluminum wire instead of copper? +
Aluminum is lighter and cheaper, making it common for large feeders and utility lines. However, it has higher resistance and lower ampacity per gauge than copper, so you need a larger gauge for the same current.
What do 0, 00, 000, and 0000 AWG mean? +
These are the largest standard AWG sizes. 0 AWG (1/0) has a diameter of about 8.25mm. Each additional zero increases the size: 00 (2/0) is about 9.27mm, 000 (3/0) is 10.40mm, and 0000 (4/0) is 11.68mm.