Electrical Load Calculator
Calculate current draw and recommended breaker size from connected electrical load.
Assumptions used in this calculation
- Not a substitute for code: Uses the standard 80% continuous-load rule as a guideline, always follow local electrical code and consult a licensed electrician.
About this calculator
Wiring a circuit to the wrong breaker size is a real safety hazard, too small and it trips constantly under normal load, too large and it won't trip before wires overheat, and the sizing math involves both Ohm's law and an electrical-code derating rule that's easy to skip when doing it by hand. This calculator divides total connected wattage by circuit voltage to find current draw in amps, then divides that current by 0.8 to apply the standard 80% continuous-load rule that codes like the NEC require, and rounds the result up to the next standard breaker size (15A, 20A, 25A, and so on) since breakers only come in fixed increments. Enter your connected load and voltage, and get a code-informed breaker recommendation in place of manually computing current and then remembering the derating factor. This is a planning guideline, not a substitute for a licensed electrician, always confirm against your local electrical code before wiring a circuit.
Worked example
2400W at 120V
Result: 20A current, 25A recommended breaker
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