MOTORS · CALCULATOR

Power and motor torque calculator

Free power and motor torque calculator: get rated operating torque from mechanical output and shaft speed. 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

Mechanical output

Shaft speed

rpm

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

THE MATH BEHIND THE ANSWER

Method & assumptions

T = 60 × 1000 × P / (2πn)

Not maximum/breakdown torque; that requires motor manufacturer curves.

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

Mechanical output: 5 kW · Shaft speed: 1,750 rpm

Rated operating torque: 27.284 N·m

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

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