Construction
Circuit Load Calculator
Check load in amps and as a percentage of circuit capacity from watts and voltage.
This result shows how much current the circuit carries and how much of the breaker rating is used, so a higher percentage means the circuit is closer to its limit and less spare capacity remains.
Formula
Current in amps = power in watts divided by voltage in volts. Load percentage = current divided by breaker rating, multiplied by 100.
How it works
Add up the watts of everything on the circuit and divide by voltage to get amps. Comparing amps with the breaker rating shows how close the circuit is to its limit. Continuous loads should stay well below the breaker rating, and any circuit change needs a qualified electrician.
Worked example
For example, a total load of 1800 watts on a 230-volt circuit gives 1800 ÷ 230 = 7.83 amps, which is 7.83 ÷ 16 × 100 = 49% of a 16-amp breaker rating.
FAQs
What if load exceeds 100%?
The breaker may trip and the circuit is overloaded. Move loads to another circuit or have an electrician assess it.
Is 80% a safe limit?
For continuous loads, staying at or below about 80 percent of rating is a common planning guideline.
Can I add loads myself?
No, electrical work should be done or verified by a qualified electrician.
Rough estimate only — consult a licensed professional for structural work before building.
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