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Wire Gauge Calculator
Find the minimum AWG wire size for a given current.
Minimum wire gauge
—
AWG.
| Ampacity | — |
|---|---|
| Current | — |
| Material | — |
| — |
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How the Wire Gauge Calculator Works
Wire has to be thick enough to carry its load without overheating. This calculator gives the smallest American Wire Gauge (AWG) copper or aluminum conductor rated for your current, using the National Electrical Code 60°C ampacity table — for example, a 20-amp copper circuit needs at least 12 AWG.
It’s a starting point, not a substitute for the full code: long runs need upsizing for voltage drop, and heat, insulation type and bundling all affect the real rating. When in doubt, consult an electrician and the NEC.
pick the smallest gauge whose ampacity meets the load current
Frequently Asked Questions
What gauge wire for 20 amps?
At least 12 AWG copper (or 10 AWG aluminum) under the NEC 60°C column.
What gauge wire for 30 amps?
10 AWG copper, or 8 AWG aluminum.
Does wire length matter?
Yes — long runs need a thicker wire to limit voltage drop, beyond the basic ampacity requirement.
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