GeneratorCalc

Free calculators for backup power

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Circuit Breaker Load Calculator (Amps)

Use this calculator to see how heavily a breaker is loaded when you run generator-powered circuits.

It uses the basic relationship P = V × I and the common rule of thumb that continuous loads stay at or below about 80% of breaker rating.

Breaker load estimate

Check breaker watt capacity, load percentage, and how that compares to the 80% guideline.

For more planning tools, you can also use the other calculators and guides on the GeneratorCalc home page.

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