Calculate wire resistance

Online calculators and formulas for calculating wire resistance

Calculate wire resistance online

On this page, the electrical resistance is calculated from the length and cross-section of a wire. The specific resistance or conductance of the wire material must be known.

Note, the resistance of the specified simple length is calculated. If you want to calculate the total resistance of a two-pole cable, e.g. a loudspeaker cable, you have to multiply the value by 2. Total resistance = forward line + return line.

The specific conductance values of the most common cables are



Copper 56.0
Silver 62.5
Aluminium 35.0

For a list of other resistivity and conductance values click here.

Wire Resistance Calculator

 What should be calculated?
Wire Length (m)
Cross-sectional area (mm2)
Wire resistance (Ω)
Wire resistance
Cross-sectional area
Wire Length
Wire conductance
Decimal places


\(\displaystyle A \) Cross-sectional area (mm2)

 \(\displaystyle l \)  Wire Length (m)

\(\displaystyle R \) Wire resistance

\(\displaystyle S \) Wire conductance

\(\displaystyle ρ \) Specific resistance

\(\displaystyle σ \) Specific conductance

Wire resistance formulas

Resistance of the wire \(\displaystyle R=\frac{ρ · l}{A}\)   \(\displaystyle =\frac{l}{σ · A}\)
Length of the wire \(\displaystyle l=\frac{R · A}{ρ}\)   \(\displaystyle =R · A · σ \)
Wire cross-sectional area \(\displaystyle A=\frac{l}{R · σ}\)   \(\displaystyle =\frac{l · ρ}{R}\)
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