Wire Resistance Calculator
Calculate a wire’s electrical resistance from its length, cross-sectional area, and material.
What this calculator does
Every wire resists the flow of electric current to some degree, depending on what it’s made of, how long it is, and how thick it is. This calculator estimates that resistance directly.
The formula
Resistance is calculated using R = ρ × L / A, where ρ (rho) is the electrical resistivity of the material (in ohm-meters), L is the wire’s length, and A is its cross-sectional area. Longer, thinner wires have more resistance; shorter, thicker wires have less.
This calculation assumes a constant temperature (resistivity values given are typical for around 20°C); resistance rises somewhat as a wire heats up. This tool is intended for general electronics education and design estimation.