Built for real work
Copper and aluminum.
Voltage Drop Calculator — Wire Size & Length
Calculate voltage drop for copper or aluminum wire by AWG, amps, and length. Free electrical voltage drop calculator.
Formula used
Vd = 2 × K × I × L / CM (single phase) K = 12.9 copper, 21.2 aluminum
Examples
Try a sample calculation
20 A, 100 ft, 12 AWG
Branch circuit
Fast and focused
Common AWG sizes.
Clear results
Step-by-step NEC formula.
Main features of Voltage Drop Calculator:
Enter the required fields—dates, amounts, percentages, or measurements as labeled.
Double-check units (currency, tax rate, height/weight) match your scenario.
Run the calculation and read the breakdown, not just the headline number.
Adjust inputs to compare scenarios, or open a related Rankify calculator for the next step.