Free Circuit Breaker Sizing Calculator
Calculate the correct breaker size for a circuit based on connected load, voltage, and NEC safety factor.
W
Recommended Breaker
25 A
Actual Current Draw20.0 A
Design Current25.0 A
Recommended Breaker vs Total Connected Load
Circuit Breaker Sizing
Amps = Watts / Volts
Continuous load: multiply by 1.25 per NEC 210.20(A). Then round up to the next standard breaker size (15A, 20A, 30A, 40A, 50A, etc.).
Example Calculation
2,400W continuous load on 120V.
- 01Amps = 2400 / 120 = 20A
- 02Design amps = 20 x 1.25 = 25A
- 03Next standard size = 25A, or use 30A breaker
Frequently Asked Questions
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