Home & DIY CalculatorsPrivate by design
Circuit Breaker Load Calculator
Enter your total connected wattage, voltage, and breaker rating to check your load against the National Electrical Code's 80% continuous-load guideline.
How to use this tool
- 1Add up the wattage of everything on the circuit.
- 2Enter your circuit voltage (commonly 120V or 240V).
- 3Enter the breaker's amp rating.
- 4See your load in amps and whether it's within the safe continuous-load limit.
Frequently asked questions
Why 80% and not 100%?+
The National Electrical Code requires continuous loads (running 3+ hours) to not exceed 80% of a breaker's rating, since breakers are rated for their full capacity only on shorter, intermittent loads.
Related tools
Keep the boring tools boring.
If this saved you five minutes of nonsense, you can help keep the free tools running.
Buy the toolbox a coffee