Enter the length, cross-sectional area, and the resistivity of a material into the calculator below to calculate the resistance of a wire.
Wire Resistance Formula
The following equation is used to calculate the resistance of a wire.
R = ρ * L / A
- Where R is the resistance in Ohms
- ρ is the resistivity of the material the wire is made of. (Ohms*meters)
- L is the length of the wire (meters)
- A is the cross-sectional area (m^2)
In this case the key value will be the resistivity of the material. This will vary depending on what a wire is made of. For example the resistivity of something like copper will be much lower than something like glass, since copper is a conductor and glass is often used as an electrical insulator.
Another way to increase the resistance of a wire is to increase it’s length. This can be seen in electrical power wires that run throughout the country. These wires are extremely long. As a result they have a large resistance and energy is lost through it’s travels. Conversely, increasing the cross-sectional area increase the resistance of a wire.