Breaker Size Calculator.

Breaker size depends on load amps and whether it's continuous. The calculator shows the recommended size — enter watts, voltage, and load type.

Watts ÷ Voltage = Amps. For continuous: Amps × 1.25. Round up to standard size. The calculator does all three steps automatically.

Yes — an oversized breaker won't protect the wiring. Always match breaker size to wire ampacity per NEC.

Depends on load, not voltage. For 4500W at 240V continuous: 18.75A × 1.25 = 23.4A → 25A breaker.

48A charger needs 60A breaker. 32A needs 40A. Use the calculator with your charger's power rating in watts.

Continuous loads (3+ hours) should not exceed 80% of breaker rating. A 20A breaker handles 16A max continuous.

Continuous loads require 125% sizing. Set "Continuous Load? = Yes" in the calculator and it applies the multiplier automatically.

No — using a smaller breaker causes nuisance tripping. Always use the correct NEC-rated size.

Enter watts and voltage in the calculator above. It converts to amps, applies the 125% rule for continuous loads, and shows the breaker.

Breaker capacity must protect the wiring based on load amperage, continuous duty, and NEC standards. The calculator ensures code-compliant sizing.