Estimate electrical cable size from load current, voltage, distance, cable material, phase type, voltage drop target, and continuous load factor. This calculator gives a planning estimate for copper or aluminum cable sizing.
Adjusted current:
The calculator starts with the load current and applies a continuous load factor when selected.
Ampacity check:
The adjusted amps are compared to a simplified cable ampacity table for copper or aluminum conductors.
Voltage drop check:
The calculator estimates voltage drop across the cable run and selects a cable size that stays within the chosen voltage drop target when possible.
A cable size calculator helps estimate cable gauge before planning an electrical project.
It can help with branch circuits, feeder cables, garage runs, shed wiring, RV circuits, solar cable estimates, low-voltage wiring, appliance circuits, and general electrical planning.
Your result shows estimated cable size, adjusted amps, ampacity, voltage drop, final voltage, cable run distance, estimated watts, cable material, phase type, and comparison scenarios.
Start with the load current, apply any continuous load factor, then select a cable size that supports the amps and keeps voltage drop within the target range.
Yes. Longer cable runs usually create more voltage drop, so a larger cable may be needed even if the amp load stays the same.
Copper has lower resistance than aluminum for the same size, so aluminum cable usually needs to be larger to carry a similar load.
No. This is a planning estimate. Final cable sizing should be verified with local electrical code, conductor insulation, terminals, conduit fill, derating, breaker size, and a qualified electrician.