Wire Gauge for Amperage Calculator

NEC ampacity: typical residential AWG sizes for current load.

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How to use this calculator

  • Enter continuous load in amps.
  • Read minimum gauge from NEC table.

About this calculator

NEC table 310.16 ampacities for typical 60°C copper conductors in residential applications. Common pairings: 14 AWG/15A, 12 AWG/20A, 10 AWG/30A. Always derate for long runs (voltage drop), bundling, and high ambient temperatures.

Frequently asked

Why "smaller AWG = bigger wire"?+
AWG number is inversely proportional to diameter. 14 AWG is thinner than 12 AWG.
60°C vs 75°C ratings?+
Standard residential: 60°C. Commercial/larger: 75°C (allows higher ampacity in same gauge).
Aluminum vs copper?+
Aluminum: cheaper, larger gauge needed for same ampacity (1 AWG larger).
When to oversize?+
Long runs (>100 ft): one size larger to avoid voltage drop. Many local codes require oversizing for kitchen 20A circuits.
Continuous vs non-continuous load?+
Continuous: 3+ hours. NEC requires sizing at 125% of continuous load. Use breaker-size-for-load for that.

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