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Horsepower & Torque Calculator

Calculate mechanical horsepower from torque and engine speed at the same operating point.

By AutomotiveCalc · Published September 9, 2026 · Method & standards

Your numbers

Example calculation

Example results are shown below. Controls become available when the calculator loads.

Mechanical horsepower285.6 hp
Power212.97 kW
Torque406.75 N·m

Calculated on your device. No account needed.

How to use this calculator

Replace the example values with your own measurements or specifications. Keep the units shown beside each label. Results update as you type; reset restores the example.

Use torque measured at the same rpm, not peak torque combined with peak-power rpm. Wheel and crankshaft measurements are different; this tool does not estimate drivetrain loss. Mechanical hp differs from metric PS.

The formula

Mechanical horsepower = torque (lb-ft) × rpm ÷ 5,252.113122. This follows power = torque × angular speed and 1 hp = 33,000 ft·lb/min.

A worked example

300 lb-ft at 5,000 rpm corresponds to about 285.60 mechanical horsepower, or 212.97 kW.

Common questions

Can I multiply peak torque by redline RPM?

Only if that torque is actually available at redline. Otherwise the calculated power is misleading.

Why do torque and horsepower cross near 5,252 rpm?

Their numerical values match there only when torque is in lb-ft and power is in mechanical horsepower.

Sources & calculation method

This tool uses the geometric or dimensional relationship shown above. Conversion constants and units are stated in the formula or explanation so the calculation can be reproduced.

Prepared with AI assistance. Formula examples and input validation have automated checks. This page has not received an independent automotive professional review. Read our review standards.