Wire Resistance Calculator

Calculate the resistance of a length of wire with the Wire Resistance Calculator and learn on the go with the integrated live example

The Wire Resistance Calculator is designed to calculate the resistance of round copper wire.

The formula to calculate resistance is:

$R=\frac{\rho l}{\pi r^2}$

Where
R = Resistance in ohms
ρ = The resistivity of the conductor (copper = 1.678 × 10^-8 ohms·metre at 20°C)
l = Conductor length in metres
r = Conductor radius in metres

Example: Find the resistance of a wire that’s 200 metres in length and 0.56mm in diameter (0.28mm radius)

$R=\frac{1.678\times 10^{-8}\times 200}{3.142\times 0.28^2}\approx \frac{0.000003356}{0.000000246}$

$R=13.626\; ohms$

Using the Wire Resistance Calculator

Conductor Diameter: Input the diameter of the wire

Conductor Length: Input the length of the wire

Selecting units: You can choose your preferred units of measurement through selecting the units cells and clicking the downwards pointing arrow to display a list of available options

Learn As You Go: This feature displays a live example of how to calculate the resistance of round copper wire using the figures that you enter