Circuit Breaker Calculator
Calculate the required breaker amperage and wire gauge for your electrical load with NEC compliance checking.
Inputs
W
%
Results
Breaker Size
20 A
Wire Gauge (AWG)12
Actual Current Draw15 A
Required Amps (w/ safety)18.75 A
Load Percentage75%
NEC 80% Rule1
Breaker Size
20 A
How to Use This Calculator
- Start by filling in the input fields below. Results update instantly as you type, so you can experiment with different values to see how they affect the outcome.
- Total Load — Total wattage of all devices on the circuit. Accepts values from 100 W to 50,000 W (default: 1,800 W).
- Voltage — Circuit voltage (120V standard, 240V for heavy appliances). Choose from: 120V, 240V. default: 120.
- Safety Factor — NEC requires 125% for continuous loads. Use 100% for non-continuous loads. Accepts values from 100 % to 200 % (default: 125 %).
- Once all inputs are set, review your results in the Results panel. Here's what each output means:
- Breaker Size — shown as a numeric value. This is the primary result of this calculator.
- Wire Gauge (AWG) — shown as a numeric value.
- Actual Current Draw — shown as a numeric value.
- Required Amps (w/ safety) — shown as a numeric value.
- Load Percentage — shown as a numeric value.
- NEC 80% Rule — shown as a numeric value.
- Explore the related calculators below if you need deeper analysis or want to approach this topic from a different angle.
Ad Placeholder
Related Calculators
Wire Gauge Calculator
Determine the recommended AWG wire gauge based on current, distance, voltage, and acceptable voltage drop.
Electrical Load Calculator
Calculate total electrical load by circuit type and determine the service panel size and main breaker needed.
Voltage Drop Calculator (Residential)
Calculate voltage drop for residential wiring and check compliance with the NEC 3% recommendation.
Amps / Watts / Volts Converter
Convert between amps, watts, and volts. Enter any two values to calculate the third, plus energy cost estimates.
Ad Placeholder