Estimate circuit breaker size from amps, watts, voltage, phase type, continuous load, power factor, and safety factor. This calculator helps with basic breaker sizing, circuit load planning, and related electrical estimates.
Load amps:
The calculator uses entered amps or converts watts or volt-amps into current based on voltage, phase type, and power factor.
Adjusted amps:
The calculator applies a continuous load factor and any extra safety factor you choose.
Breaker size:
The adjusted current is rounded up to the next common breaker size.
A breaker size calculator helps estimate the overcurrent protection size for a load before planning a circuit.
It can help with outlet circuits, lighting circuits, appliances, workshop tools, heaters, subpanels, feeders, garage circuits, shed wiring, and general electrical planning.
Your result shows recommended breaker size, calculated load amps, adjusted amps, estimated watts, breaker load percentage, estimated wire size, voltage, phase type, power factor, and comparison scenarios.
Estimate the load current, apply any required continuous load factor, then choose a breaker size that is properly matched to the wire, equipment, and code requirements.
A common planning estimate is to multiply the continuous load by 125%, then select the next suitable breaker size. Final sizing depends on code and equipment requirements.
No. Increasing breaker size without confirming wire size and circuit rating can create a fire hazard. Breaker size must be matched to the conductor and equipment.
No. This is a simplified planning tool. Always verify breaker size, wire size, equipment nameplate ratings, panel capacity, derating, and local code with a qualified electrician.