# Wire Resistance Calculator

Calculate the resistance of a length of wire with the Wire Resistance Calculator, and learn how 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)

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

$R=13.626\; ohms$

Enter the Conductor Diameter and Conductor Length

## How To Calculate Wire Resistance

Enter some values to get started!

### Using the Wire Resistance Calculator

Conductor Diameter: Input the diameter of the wire

Conductor Length: Input the length of the wire

How To Calculate Wire Resistance: This feature displays a live example of how to calculate the resistance of round copper wire using the figures that you enter

The result is calculated and updated automatically as you enter different numbers or change between the input fields. If the calculated result hasn’t updated after you’ve finished entering your values, click or tap on the result.

Reference: Wikipedia