MOTORS · CALCULATOR

Motor FLA calculator

Free motor FLA calculator: get estimated full-load current from output power, voltage and power factor. 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

Output power

Voltage

SupplyPower factor

Efficiency

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

THE MATH BEHIND THE ANSWER

Method & assumptions

I = hp × 745.7 / (k × V × PF × η)

Use required adopted-code FLC tables for protection selection; engineering estimate only.

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

Output power: 10 hp · Voltage: 230 V · Supply: Single phase · Power factor: 0.85 · Efficiency: 90 %

Estimated full-load current: 42.381 A

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

Explore the motors branch →See the related electrical concepts →

Estimating and invoicing tool

Ampxa is developing an estimating and invoicing application for electrical contractors. The list below receives notice when it opens.