Online calculators and formulas for calculating wire resistance
On this page, the electrical resistance is calculated from the length and crosssection 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 twopole 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
Material
Conductance
Copper 56.0 Silver 62.5 Aluminium 35.0
For a list of other resistivity and conductance values click here.

\(\displaystyle A \) Crosssectional area (mm^{2})
\(\displaystyle l \) Wire Length (m)
\(\displaystyle R \) Wire resistance
\(\displaystyle S \) Wire conductance
\(\displaystyle ρ \) Specific resistance
\(\displaystyle σ \) Specific conductance
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 crosssectional area  \(\displaystyle A=\frac{l}{R · σ}\) \(\displaystyle =\frac{l · ρ}{R}\) 
