Estimate circuit breaker size, breaker load percentage, remaining capacity, continuous load limit, amps, watts, volt-amps, and basic trip-risk range from your electrical load.
Load current:
The calculator uses entered amps or converts watts and volt-amps into amps using voltage, phase type, and power factor.
Breaker load:
The load current is compared to the selected breaker size to estimate breaker load percentage and remaining capacity.
Breaker sizing:
For new breaker estimates, adjusted amps are rounded up to the next common breaker size.
A circuit breaker calculator helps estimate whether a breaker is appropriately loaded and what breaker size may be needed for a planned circuit.
It can help with outlet circuits, lighting circuits, heaters, appliances, workshop tools, garage circuits, shed wiring, subpanels, feeders, and general electrical planning.
Your result shows breaker status, load amps, adjusted amps, breaker load percentage, remaining amps, 80% continuous limit, recommended breaker size, estimated wire size, watts, volt-amps, and comparison scenarios.
Divide the load amps by the breaker amps, then multiply by 100. For example, 16 amps on a 20 amp breaker is 80% breaker load.
For many continuous load planning estimates, a breaker is commonly limited to 80% of its rating unless the equipment and installation are rated otherwise.
Not unless the wiring and circuit are rated for 20 amps. Upsizing a breaker without verifying the conductor size can create a fire hazard.
No. This is a simplified planning tool. Always verify breaker size, wire size, equipment ratings, panel capacity, derating, and local electrical code with a qualified electrician.