Wire Gauge Converter
Convert AWG to mm² and diameter, with copper resistance and a chart.
About this tool
Choose AWG, cross-section in mm² or diameter in mm. The tool converts to the others, finds the nearest AWG and the smallest AWG at least as large, and lists copper resistance. The chart covers 0000 to 40 AWG with the nearest metric cable size.
AWG and metric wire sizes
American Wire Gauge numbers count backwards: a higher number is a thinner wire. The diameter is d = 0.127 mm × 92^((36 − AWG) ÷ 39), so every 6 gauges halves the diameter and roughly every 3 gauges halves the cross-section; sizes thicker than 1 AWG are written 0, 00, 000 and 0000. Most of the world sizes cable by cross-sectional area in mm² instead. 12 AWG is 2.05 mm across and 3.31 mm²; 10 AWG is 5.26 mm²; a 2.5 mm² cable sits between 14 AWG (2.08 mm²) and 13 AWG (2.63 mm²). When substituting, always choose the AWG that is at least as large as the metric size. Copper resistance at 20°C is 17.24 Ω·mm² per km, divided by the area, so 12 AWG is about 5.2 Ω/km (1.59 Ω per 1,000 ft), which determines voltage drop. Honest limits: safe current (ampacity) depends on insulation rating, installation method, grouping and ambient temperature, and is set by codes such as the NEC, BS 7671 and IEC 60364, so it isn't shown here. The voltage drop calculator and the PCB trace width calculator are related.
Frequently asked questions
What is 12 AWG in mm²?
About 3.31 mm², with a diameter of 2.05 mm.
What AWG is 2.5 mm²?
Between 14 AWG (2.08 mm²) and 13 AWG (2.63 mm²). Use 13 AWG or thicker as an equivalent; 12 AWG is the common choice.
Why do bigger AWG numbers mean thinner wire?
The numbers came from the number of drawing steps used to make the wire; more steps produced a thinner wire.
Does this show how many amps a wire can carry?
No. Ampacity depends on insulation, installation and local wiring codes, so check your code's tables.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.