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Calculator Collection

Circuit Breaker Size Calculator vs Transformer Sizing Calculator

Two calculators for the same neighbourhood of questions. Here is what each measures, what you feed in, and where you'd reach for one over the other.

Electrical Home

Circuit Breaker Size Calculator

Determine the correctly sized circuit breaker for any electrical load, accounting for continuous versus non-continuous use, ambient temperature, and safety margins. Use it before wiring a new circuit or replacing a breaker.

Answers
Minimum Breaker Size (amps)
Inputs
Total Circuit Load, Load Type, Ambient Temperature, Safety Factor
Electrical

Transformer Sizing Calculator

Determine the minimum transformer kVA rating needed for a given electrical load, accounting for demand factor, power factor, safety margin, and ambient temperature derating. Use this when specifying or replacing distribution transformers on new or existing electrical systems.

Answers
Required Transformer Size (kVA)
Inputs
Total Connected Load, Demand Factor, Safety Factor, Load Power Factor, Ambient Temperature

At a glance

Circuit Breaker Size CalculatorTransformer Sizing Calculator
CategoryElectrical HomeElectrical
AnswersMinimum Breaker SizeRequired Transformer Size
Inputs45
Result unitampskVA

When to use each

Determine the correctly sized circuit breaker for any electrical load, accounting for continuous versus non-continuous use, ambient temperature, and safety margins. Use it before wiring a new circuit or replacing a breaker.

Determine the minimum transformer kVA rating needed for a given electrical load, accounting for demand factor, power factor, safety margin, and ambient temperature derating. Use this when specifying or replacing distribution transformers on new or existing electrical systems.

Compare page seeded from editorial siblings — both calculators list each other as related.