FREE ELECTRICITY TOOL
Voltage Drop Calculator
Estimate voltage drop, maximum cable distance, or a preliminary conductor size for an electrical circuit.
System Parameters
Input Parameters
Results update automatically when inputs change.
Results
How to use the calculator
- Select the circuit type, conductor material, and cable-length unit.
- Choose whether to calculate minimum conductor size, maximum distance, or voltage drop.
- Enter current, supply voltage, cable length, wire size when applicable, and the allowed voltage-drop percentage.
- Review the results, which update automatically when you change the inputs.
Assumptions and limitations
This tool uses approximate conductor resistance values and a simplified voltage-drop model. Cable length is treated as one-way length; the model accounts for the return path for DC and single-phase circuits. Three-phase calculations use a √3 factor.
AC cable impedance, power factor, conductor temperature, terminals, installation conditions, ampacity, overcurrent protection, and local electrical codes can affect real-world selection. The minimum-size result is only a preliminary voltage-drop estimate, not an ampacity recommendation or code-compliance approval. Consult a qualified electrician for actual installations.
