Electrical Wire Gauge Calculator
Determine the correct wire gauge for your circuit based on amperage and distance.
Avoid voltage drop issues with the right wire size.
Recommended Wire Gauge
Wire gauge selection depends on the circuit amperage and the distance from the electrical panel to the load. Longer distances require thicker wire to prevent excessive voltage drop.
Voltage Drop (%) = (2 × Length × Current × Resistance per ft) / Voltage × 100
The NEC recommends keeping voltage drop under 3% for branch circuits and under 5% total.
Unit conversions:
Imperial: Distance in feetMetric: Distance in meters (converted to feet internally: 1 m = 3.281 ft)
Standard copper wire gauge ratings (at 75°C):
| AWG | Max Amps | Typical Use |
|---|---|---|
| 14 | 15A | Lighting circuits |
| 12 | 20A | General outlets |
| 10 | 30A | Dryers, AC units |
| 8 | 40A | Ranges, large AC |
| 6 | 55A | Sub-panels, large appliances |
| 4 | 70A | Sub-panels |
| 2 | 95A | Large sub-panels |
Tips:
- Always consult local electrical codes — they may differ from NEC guidelines
- Aluminum wire requires one gauge larger than copper for the same ampacity
- Use THHN/THWN rated wire for most residential applications