〰️ Wire Resistance Calculator for Electrical
Estimate conductor resistance from resistivity, length and area.
This free tool helps you turn project measurements into a practical planning estimate. Enter values in Vaelden’s interactive calculator, review the result, and confirm important assumptions against supplier data, measurements, codes or qualified advice before committing materials or money.
Open the Wire Resistance calculator →
How to calculate wire resistance
Method: Conductor resistance = resistivity × length ÷ cross-sectional area
- Choose resistivity for the conductor material and temperature.
- Use actual conductor path length.
- Use metallic cross-sectional area in consistent units.
Worked example
Using these planning inputs:
- Material resistivity: 0.01724 Ω·mm²/m
- Conductor length: 20
- Cross-sectional area: 2.5 mm²
Conductor resistance: 0.13792 Ω
Reality check: Real resistance rises with temperature and connection resistance; use manufacturer data for safety-critical design.
Before you calculate
Use consistent units and the best measured inputs available. Real materials, equipment, site conditions and tolerances can change the result. Vaelden shows planning estimates; regulated, structural, electrical, plumbing, pressure and other safety-critical work still requires appropriate local compliance and professional advice.