Voltage Drop Calculator
Calculate voltage drop for electrical circuits. Supports copper/aluminum, AWG/mm², and instant conversion.
Result
Voltage Drop:
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Voltage Drop %:
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Voltage at Load:
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Voltage Drop Tips
Formula
VD = (2 × L × R × I) / 1000. L = length, R = resistance, I = current. For single-phase, use 2×length.
NEC Recommendation
Voltage drop should not exceed 3% for branch circuits (total 5% feeder+branch).
Examples
100 ft, 20A, 120V, 12 AWG Cu: VD ≈ 3.8V (3.2%).