MOTORS · CALCULATOR

Motor power factor calculator

Free motor power factor calculator: get power factor from input active power, voltage and current. The formula is shown; verify against the NEC.

Written by Chameera Sampath · Not yet reviewed by a licensed electrician. See the methodology.

US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗

Project inputs

Measurements

Input active power

Voltage

Current

Supply

Updates as inputs change. Unit changes preserve the same physical values.

THE MATH BEHIND THE ANSWER

Method & assumptions

PF = Pin / (k × V × I)

Input electrical power, not shaft power. Result above 1 means inconsistent inputs.

Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.

Sources and validation →

Worked example

Input active power: 2 kW · Voltage: 230 V · Current: 20 A · Supply: Single phase

Power factor: 0.435

This example uses the stated inputs; results for the entered values appear above.

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