Science & Engineering

Wire Resistance (Gauge, Length & Temperature)

Find the resistance of a wire from its material, length, and cross-section. You can enter AWG gauge, area in mm2, or diameter, and add a temperature for automatic correction.

How to use
  1. Pick the wire material, such as copper or aluminium.
  2. Enter length and the cross-section as AWG gauge, mm2, or diameter.
  3. Add a temperature to apply the alpha correction.
For study and estimation. Verify against authoritative data before relying on a result.
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Worked examples

WireResistanceNote
12 AWG copper, 100 ft0.16 ohmcommon house wiring
14 AWG copper, 100 ft0.25 ohmlighting circuits
12 AWG aluminium, 100 ft0.26 ohmhigher than copper
10 AWG copper, 100 ft0.10 ohmhigh-current run

Common questions

Why does wire resistance rise with temperature?

Heat makes the metal's atoms vibrate more, which scatters electrons. For copper the resistance climbs about 0.39% per degree Celsius.

Does a thicker wire have more or less resistance?

Less. Resistance is inversely proportional to cross-section, so a 10 AWG wire has about half the resistance of a 13 AWG wire of the same length.

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