Circuit Breaker Size Calculator
Estimate calculated breaker rating from continuous load current and design margin.
Calculator
Enter the values below. Every quantity identifies its unit or meaning.
Result
Calculated from your inputs.
Electrical & Energy reference calculator
These results are for general calculation and planning. Actual electrical installations, conductor sizing, protection settings, solar systems, batteries and generators should be designed and verified against applicable codes, manufacturer specifications and site conditions.
How to use this calculator
What to enter
Enter or select the following as requested: Continuous load current; Design margin. Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The electrical or energy result is calculated from the voltage, current, power, capacity, runtime, efficiency, or rate values entered. Check whether values are AC or DC, whether power factor and efficiency are included, and that voltage, current, energy, and capacity units are consistent.
When to use it
Use this for preliminary energy use, battery, solar, or electrical-load planning. Do not use a calculator result alone to size or install safety-critical electrical equipment; follow applicable codes and qualified professional guidance.