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Calcimator

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
How to Use This Calculator
  1. Enter the Total Load in Watts for all devices on the circuit.
  2. Select System Voltage (120V or 240V).
  3. Set the Safety Factor (typically 1.25 per NEC 80% rule).
  4. Review Recommended Breaker Size (amps) and Recommended Wire Gauge (AWG).
  5. Select the next standard breaker size up (15, 20, 30, 40 amp) from the recommendation.
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