Electronics / Wire
Wire Gauge Converter (AWG ↔ mm²)
Convert American Wire Gauge sizes from 4/0 to 40 AWG to diameter, cross-section in mm², and copper resistance per km, or find the AWG size closest to a metric cable in mm².
Wire Gauge Converter (AWG ↔ mm²): AWG sizes follow a formula: diameter = 0.127 mm × 92^((36 − gauge) ÷ 39), with 0, 00, 000, and 0000 counted as 0, −1, −2, and −3. Each 6 gauges halve the diameter and each 3 gauges roughly halve the area. Resistance is worked out for copper at 20 °C, 1.724 × 10⁻⁸ Ω·m. Runs 100% locally in your browser with zero server file uploads.
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AWG sizes come from a formula: each step of 6 gauges halves the diameter, and 36 AWG is 0.127 mm. A smaller number is a thicker wire. How much current a wire may carry depends on its insulation, how it is installed, and the local electrical code, so look that up in the code that applies where you are rather than relying on a single table; when in doubt, choose the thicker wire.
Common sizes
22 AWG is 0.326 mm², typical for hook-up and jumper wire; 18 AWG is 0.823 mm²; 14 AWG is 2.08 mm² and 12 AWG is 3.31 mm², both common in US house wiring; 10 AWG is 5.26 mm².
Metric cables come in steps of 0.75, 1, 1.5, 2.5, 4, and 6 mm² and so on, which do not line up exactly with AWG.
Voltage drop
A long run loses voltage: twice the length (there and back) times the resistance per metre, times the current. 10 m of 12 AWG carrying 10 A loses about 20 m × 5.21 mΩ × 10 A ≈ 1.04 V.
For the resistance of a PCB trace instead, use the PCB trace width calculator.
How to use it
- Choose AWG to mm², or mm² to AWG.
- Pick the gauge, or type the cross-section of a metric cable.
- Read the diameter, area, and resistance, or the nearest AWG size.
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Frequently asked questions
What AWG is 2.5 mm²?
Between 13 and 14 AWG: 13 AWG is 2.63 mm² and 14 AWG is 2.08 mm², so a 2.5 mm² cable is close to 13 AWG.
Is a bigger AWG number thicker?
No, thinner: 10 AWG is thicker than 20 AWG, because the number came from how many times the wire was drawn through a die.
How much current can a wire carry?
It depends on the insulation, how the cable is installed and bundled, and the ambient temperature, so use the tables in the electrical code that applies where you are.
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