The Wire Resistance Calculator computes the resistance of a conductor from its resistivity, length and area, with correction for operating temperature, and adds voltage drop and power loss when a current is entered.
Wire Resistance Calculator
Calculate the DC resistance of a wire from material, length and cross-section, with temperature correction. Optionally show voltage drop and power loss at a load current.
Inputs
Result
--
resistance (ohm)
--
drop at current (V)
About Wire Resistance Calculator
Features
- Copper and aluminum
- Length in feet or metres
- Size by AWG or mm2
- Temperature correction
- Voltage drop and loss with current
How to Use
- Pick material, length, unit and wire size.
- Set temperature and optional current.
- Read resistance, drop and loss.
Examples
Example: 100 m of 10 AWG copper at 20C, 30 A -> 0.328 ohm, 9.8 V drop, 295 W loss.
Benefits
- Estimate losses before installing
- Check resistance for heating and drop
Frequently Asked Questions
What does this calculate?
It gives the resistance of a wire run from its material, length and cross-section, including temperature effects.
Which materials are supported?
Copper and aluminum, using standard resistivity at 20C with temperature coefficients.
What if I add a current?
The tool also shows the voltage drop (I x R) and power loss (I^2 x R) for one conductor.
Is my data saved?
No. All math runs in your browser.