Voltage Drop Calculator

Calculate voltage drop, load voltage, wire resistance, power loss, and voltage drop percentage for DC and AC circuits.

Circuit Settings

Input Values

°C

Voltage Drop Result

Voltage Drop
1.72 V
14.34% Voltage Drop
Voltage Drop
1.72 V
Drop Percentage
14.34%
Load Voltage
10.28 V
Cable Resistance
0.172 Ω
Current
10 A
Cable Power Loss
17.2 W
Transmission Efficiency
85.66%

Voltage Drop Visualization

Supply
Drop
Supply: 12 V Load: 10.28 V

Calculation Steps

Enter the circuit values and click Calculate.

Voltage Drop Formulas

Wire Resistance:

R=ρ × L / A

Where:
ρ=conductor resistivity
L=conductor length
A=conductor cross-sectional area
DC Voltage Drop:

Vdrop=I × R
Single-Phase AC Voltage Drop:

Vdrop≈ I × R × PF

For a simple resistive approximation.
Three-Phase Voltage Drop:

Vdrop≈ √3 × I × R × PF

For a simplified resistive calculation.
Voltage Drop Percentage:

Drop %=(Vdrop/ Vin) × 100
Load Voltage:

Vload=Vin− Vdrop
Power Loss:

Ploss=I² × R

Conductor Resistivity

MaterialResistivity at 20°CTypical Use
Copper≈ 1.724 × 10⁻⁸ Ω·mPower and electrical wiring
Aluminum≈ 2.826 × 10⁻⁸ Ω·mPower distribution and larger conductors

Temperature Correction

Conductor resistance changes with temperature. For many metallic conductors, resistance increases as conductor temperature rises.

RT=R20× [1 + α(T − 20)]

This calculator applies a temperature correction to the conductor resistance using an approximate temperature coefficient.

Example Calculation

Consider a 12 V DC circuit carrying 10 A through a 10 m cable using a 2.5 mm² copper conductor.

R=ρ × L / A

R ≈ 1.724 × 10⁻⁸ × 20 / 2.5 × 10⁻⁶

R ≈ 0.138 Ω
Vdrop=I × R

Vdrop=10 × 0.138

Vdrop≈ 1.38 V