Voltage Drop Calculator
Estimate AC voltage drop for common copper and aluminum conductor sizes over a specified one-way circuit length. Choose single-phase or three-phase and compare volts dropped with percent voltage drop.
Simplified resistance-based estimate. It does not include conductor reactance, temperature correction, parallel conductors, installation effects or source impedance.
How this tool works
Single-phase drop ≈ 2 × L × I × R. Three-phase drop ≈ √3 × L × I × R, with conductor resistance converted to ohms per foot.
Example
A long feeder with higher current or smaller conductor resistance will experience more voltage drop. Increasing conductor size lowers resistance and drop.
Common questions
Does this include reactance?
No. This is a simplified resistance-based estimate. Long feeders, large conductors and power-factor-sensitive studies may require full impedance.
Can I use this for final design?
Use it for screening and checks; final design should use project-specific conductor data, temperature, installation method and governing code.