Voltage Drop Calculator

Helps determine the proper wire size for an electrical circuit based on the voltage drop and current carrying capacity of an electrical circuit.

Calculate Your Voltage Drop

Determines wire size to meet specific voltage drop limits or calculates voltage drop for a specific conductor run. When sizing conductors, calculations limits wire size to voltage drop and NEC ampacity. Southwire's Voltage Drop Calculator is designed for applications using AWG and KCMIL sizes only. How to calculate voltage drop, you ask? Download our mobile apps or enter your values in the web calculator below!

Download for Mobile

Android     iOS

System Parameters


Power Factor


Units for Length of Cable Run




Input Parameters


Conductor Size

Voltage (volts)

Max Voltage Drop (%)

Current at end of cable run (amps)

Parallels (sets)

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