Wire Resistance Calculator

With the wire resistance calculator, you will be able to easily find the resistance and conductance of different wires based on their length, material, and cross-sectional area.

We have paired this calculator with an explanation of different areas related to this topic, such as:

• How to find the resistance of a wire;
• How to calculate the resistance of a copper wire using the wire resistance formula; and
• How to calculate the length of a wire using resistance.

Keep reading to learn more!

Resistance and resistivity are two similar properties of an object. However, they are not precisely the same.

Resistivity ρ describes the opposition to the flow of charged particles through an object, and it's an intrinsic property of the material which doesn't depend on the wire's dimensions.

Similarly, resistance σ refers to how strong a wire of specific dimensions (length and area) resists the flow of electrons.

The wire resistance calculator also has a field for conductance, which is the inverse of resistance.

Don't worry. These concepts will become clear once you understand their formulas.

The resistance for a straight wire can be calculated with the following equation:

where:

• $\rho$ is the material's resistivity, in ohm-meters $Ω \cdot m$;
• $L$ is the wire's length, in meters;
• $A$ is the cross-section area, in square meters $m^{2}$; and
• $R$ is the resistance, in ohms $Ω$.

Another concept, conductivity, is the inverse of resistivity, and its a measure of how easy it is for current to flow through a material:

Likewise, conductance is the inverse of resistance:

and their units are siemens per meter and siemens, respectively.

Assume we have a copper wire with a $40\ \text{mm}^{2}$ cross-section area, a known resistance value, say $0.05\ \Omega$, and we want to find how long it is.

We can obtain the length of this wire by rearranging the equation of the wire resistance formula:

The resistivity of Copper at $10\ \text{°C}$ is $1.68\times10^{-8}\ \Omega \cdot \text{m}$. Now, we can simply replace each parameter with our data in the equation above to get:

Or you can input the information in the wire resistance calculator, and our tool will automatically find any missing parameter!