Electrical Wire Gauge Calculator (AWG)
Calculate the correct wire gauge for your electrical project based on amperage, distance, and voltage. NEC compliant.
Choosing the Right Wire Size
Wire gauge must match the circuit amperage — undersized wire overheats and causes fires. NEC (National Electrical Code) minimums for copper: 15A → 14 AWG, 20A → 12 AWG, 30A → 10 AWG, 40A → 8 AWG, 50A → 6 AWG. For long runs (over 50 feet), voltage drop becomes a concern — upsize one gauge to keep voltage drop under 3%. Aluminum wire requires 2 sizes larger than copper for the same amperage.
Voltage Drop and Long Runs
NEC recommends keeping voltage drop below 3% for branch circuits and 5% total (feeder + branch). On a 120V circuit, 3% is only 3.6 volts. Long wire runs increase resistance, causing lights to dim and motors to overheat. At 100 feet on a 20A/120V circuit, 12 AWG copper has about 3.2% voltage drop — borderline. Use 10 AWG for runs over 75 feet on 20A circuits.
Wire size calculator gets 25K monthly searches from DIYers and electricians. The search spikes during renovation season (spring-fall). Users are in active project mode and often explore related electrical and home improvement calculators.
