Voltage Drop Calculator

Wire type:
Wire diameter size:
Wire/cable length (one way):
Current type:
Voltage in volts:
Current in amps:
Voltage drop in volts:
Percentage of voltage drop:
Wire resistance:

Voltage Drop Calculations

Voltage drop is the voltage loss occurring due to circuit impedance. It is the decrease in electrical potential along the path of current flowing through an electrical circuit. Voltage Drop Calculator calculates voltage drop, percentage voltage drop, and wire resistance of an electrical circuit, based on wire size, current type, voltage, and current.

Voltage Drop Formula

Voltage drop calculations are mainly performed for the following current types- DC, single phase, and 3 phase.

DC/Single Phase Calculations:

Voltage drop for DC/Single Phase is given by-

Vdrop (V) = I(A) × R(Ω)

Vdrop (V) = I(A) × (2 × L(m) × R(Ω/km) / 1000(m/km))

3 Phase Calculations :

Voltage drop for 3 phase is given by-

Vdrop (V)  = √3 × I(A) × R(Ω)

Vdrop (V) = 1.732 × I (A) × (L(m) × R(Ω/km) / 1000(m/km))


Vdrop (V) = Voltage drop in volts.

 I(A)       = Current in amperes.

 R(Ω)         = Resistance in ohms.

L(m)       = Wire length in meters.

Wire Resistance Calculations

Wire resistance of  wire is calculated by the following formula:

R (Ω/kft) = 0.3048 × 109 × ρ(Ω·m) / (25.42 × A (in2) )

R (Ω/kft) =Resistance in ohms/kft.

ρ(Ω•m) = Wire resistivity in ohm-meter.

A (in2 = Cross-sectional area in square inches.

After clicking on Calculate button, calculated voltage drop, percentage voltage drop and wire resistance is displayed within few seconds.