Wire Size Calculator
Find the minimum AWG wire gauge that meets both your voltage-drop limit and standard ampacity ratings.
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Results
- Minimum wire size
- 8 AWG
- Ampacity at this size
- 50 A
- Voltage drop at this size
- 2.51 V (2.09%)
- Voltage at the load
- 117.49 V
Guidance only — not a substitute for the NEC or local electrical code. Derating for conduit fill, ambient temperature, and terminations is not applied; consult a licensed electrician for actual installations.
About Wire Size Calculator
Enter the load current, run length, voltage, and allowed percentage drop, and the calculator walks the AWG table from 14 up to 4/0 to find the smallest conductor that satisfies both the drop limit and the ampacity rating for your chosen insulation temperature (standard 60/75/90°C columns).
The ampacity table is editable, so you can substitute derated values for hot ambients, bundled cables, or your local code's numbers.
Common uses
- Size the feeder for a subpanel, well pump, or EV charger run
- Pick wire for low-voltage solar and battery runs where drop dominates
- Compare copper vs aluminum for a long run
Limitations
- Guidance only — not a substitute for the NEC or local electrical code. Termination ratings, conduit fill, and ambient derating are not applied automatically; consult a licensed electrician for real installations.