What extension cord gauge do I need?

It depends on cord length, amp draw, voltage, and the acceptable voltage drop. Longer cords and higher amps usually need heavier, lower-number AWG wire.

Is 12 AWG heavier than 14 AWG?

Yes. Lower AWG numbers are heavier wire. A 12 AWG cord is heavier than a 14 AWG cord and usually has less voltage drop at the same length and load.

Should cord length be one-way or round-trip?

Enter the physical one-way cord length from outlet to tool. A voltage drop calculation accounts for the electrical path out and back.

Power guide

Extension cord gauge calculator guide for length, amps, and voltage drop.

A cord that reaches is not always a cord that should be used. Long cords, high amp loads, and light wire gauge can create voltage drop that affects tools, chargers, pumps, compressors, and temporary generator setups.

Open voltage drop calculator Power calculators

How to choose extension cord gauge

Enter the one-way cord length from power source to equipment.
Enter the amp draw from the tool, charger, appliance, or nameplate.
Choose the voltage: commonly 120V or 240V depending on the setup.
Compare AWG sizes and keep voltage drop low enough for the load.
Use extra caution with motors, compressors, pumps, saws, and generator power.

Common gauge mistakes

Using length only

Length matters, but amp draw matters too. A short cord for a small charger is not the same as a long cord for a compressor.

Mixing up AWG numbers

Lower AWG means heavier wire. 10 AWG is heavier than 12 AWG, and 12 AWG is heavier than 14 AWG.

Ignoring startup loads

Motor loads may start hard or run poorly with too much voltage drop. Treat compressors, pumps, and saws more cautiously.

Generator cords and temporary power

Generator setups can still suffer from voltage drop when cords are long or undersized. Use the actual voltage and expected amps, then check that plugs, receptacles, transfer equipment, and generator capacity are appropriate for the use.