Wire Gauge Calculator
Find the right AWG wire gauge for your current and distance, and check the resulting voltage drop.
Recommended gauge
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Voltage drop at that gauge —
Percent drop —
A general guide based on common ampacity and the 3% voltage-drop rule — always follow local electrical code and consult a licensed electrician for actual installations.
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How it works
Recommended gauge sized to keep current within safe ampacity and voltage drop under 3%Frequently Asked Questions
What wire gauge do I need for 20 amps?
12 AWG copper is the standard choice for 20A circuits at typical household distances, rated for 20A continuous use in most residential wiring. Longer runs may need a thicker gauge purely to control voltage drop, even if ampacity alone would allow a thinner wire.
Does wire gauge get bigger or smaller with the number?
Smaller AWG numbers mean thicker wire: 10 AWG is thicker (carries more current) than 14 AWG. It's a historical numbering quirk that trips up almost everyone at first.
Why does distance affect wire gauge choice?
Longer wire runs have more total resistance, causing more voltage drop for the same current. A load that's fine on 12 AWG at 10m might need 10 AWG or thicker at 50m to keep voltage drop under the recommended 3%.