Voltage Drop Calculator
Calculate voltage drop over a wire run given current, wire length, and AWG gauge. Check NEC 5% compliance.
How It Works
Calculate voltage drop over a wire run given current, wire length, and AWG gauge. Check NEC 5% compliance. Enter your values above and click Calculate to get instant results.
Formula
V_drop = 2 × I × R(Ω/kft) × L(ft) / 1000
Quick Examples
- 15A, 75ft, AWG 12 at 120V → 3.56V drop (2.97%)
- 20A, 100ft, AWG 10 at 240V → 4.0V drop (1.66%)
Frequently Asked Questions
How do I reduce voltage drop?
Use a larger wire gauge (lower AWG number), shorten the wire run, reduce the load current, or increase the circuit voltage.
Does voltage drop matter for LED lights?
Yes. LED drivers are sensitive to input voltage. Keep voltage drop under 3% for LED circuits to prevent flickering and premature failure.