Handy Voltage drop calculator


> Voltage Drop Calculator for AC single phase and DC circuits

Cable Size Calculator

Required size at 25°C cable temperature Length (metres)
Max current (amps)
Allowable voltage drop (volts)
Required Cable size (mm²)
Required size at other temperatures Cable Temperature (°C)
Required Cable size (mm²)

Cable Voltage Drop Calculator

Set Cable size from strands Strand diameter (mm)
Strand count
Set Cable size from AWG/B&S cable size
DC Voltage drop at 25°C cable temperature Cable size (mm²)
Length (metres)
Max current (amps)
Voltage drop (volts)
DC Voltage drop at other temperatures Cable Temperature (°C)
Voltage drop (volts)
Approx AC 50Hz Voltage drop at other temperatures
Voltage drop (volts)

Notes: Cable temperature is the actual temperature of the copper, not the ambient air temperature. Cable length is the total circuit length.

AC Voltage drop calculation is approxmately 10.02% larger than dc values for cables sizes between 2.5mm2 to 25mm2 at 50Hz. For larger cables the voltage drop gets worse, eg:- 50mm2 18%, 120mm2 22%, 150mm2 29.4%, 300mm2 68.4%, 630mm2 is a crazy 278.5%. This means that large conductors at 50Hz become a waste of copper, due to skin effect.

Copyright 2012 Advise:- This calculator is completely FREE and may be used in ANY manner.