Electrical calculator
Voltage Drop Calculator
Estimate voltage loss in a copper wire run and see the voltage expected at the load.
What the calculator includes
The wire length is doubled to include the outgoing and returning conductors. The estimate uses typical copper resistance values and does not replace an ampacity, insulation, temperature, fault current, code, or protection calculation.
Do not choose wire by voltage drop alone
- Wire must also be large enough for the current and installation conditions.
- Connections, terminals and switches add resistance.
- Motors and other loads may draw much more current at startup.
- Building and vehicle wiring rules differ.