Voltage Drop Calculator
Voltage drop and end voltage for copper or aluminium cables in DC, single- and three-phase circuits.
Inputs
V
A
m
mm²
Results
- Voltage drop
- 3.59 %
- Voltage drop
- 8.26 V
- Voltage at load
- 221.7 V
Formula
Single-phase / DC: Vd = 2 × I × L × ρ ÷ A
Three-phase: Vd = √3 × I × L × ρ ÷ A
ρ Cu = 0.0172, Al = 0.0282 Ω·mm²/m
Assumptions & limits
- Resistance at 20 °C; conductors at operating temperature drop ~20% more.
- Reactance ignored (fine for small cables).
Worked example
2 × 20 × 30 × 0.0172 ÷ 2.5 = 8.26 V = 3.59%.