Test & Soldering Equipment On-line Store

D.E.V.I.C.E.
(Wiki)Calculators
Services

Circuit Breaker Size Calculator

When you install an electrical appliance (e.g. washer or dryer), the question arises: "What circuit breaker size does a washer need?" Circuit breaker size calculator is an easy-to-use online tool to estimate the breaker size you need to protect your electrical appliances from an overload. A circuit breaker is rated in amperes, and the rating tells us how much current can safely flow through the breaker without causing it to trip.

Generally, you should size a breaker for 125% of the load (25% safety factor). This calculator allows you to input up to 5 different electrical appliances to estimate the total load the breaker will need to protect.

To calculate the total load this tool uses the following equations:

For DC circuit:
I = W / V
For AC 1-phase circuit:
I = W / (V × PF)
For AC 3-phase circuit:
I = W / (V × PF × √3)

where: I — resulting current; W — appliance's wattage; V — voltage; PF — power factor.

Please use this calculator as a starting point only! Allow a licensed electrician to install the correct circuit breaker size for your appliances!

Frequently Asked Questions

How to calculate breaker size for a refrigerator?

How to calculate breaker size for a refrigerator?
Step 1: Gather Refrigerator Specifications A standard household refrigerator (e.g., 20–25 ft³) typically has: Current Type: Single-phase Voltage: in the U.S. — 120 V Power Consumption: around 600 watts Safety Factor: recommended 25%–50% to account for compressor startup current Step 2: Enter the Data in the Calculator System Type: Single-phase Voltage: 120V Wattage: 600W Safety Factor: 25% (or up to 50% for older refrigerators) Result: So, a 10-amp circuit breaker is suitable for a dedicated refrigerator line — which is standard for residential use in Florida. Up