Horsepower Calculator

Calculate engine horsepower from torque & RPM, vehicle performance, or convert between power units.

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ft-lb
Engine torque in foot-pounds.
rpm
Engine speed in revolutions per minute.
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Horsepower
0HP

Watts

0

W

Kilowatts

0

kW

BTU/hr

0

BTU/hr

Metric HP

0

PS

Documentation

How It Works

Horsepower is a unit of power that measures the rate at which work is done. It was defined by James Watt as 33,000 foot-pounds per minute to compare steam engine output to draft horses.

This calculator supports three modes: calculating HP from torque and RPM (dynamometer style), estimating HP from quarter-mile time and vehicle weight, and converting between power units.

Formulas

1 HP = 745.7 W = 0.7457 kW = 2544.43 BTU/hr

Last Updated: February 28, 2026

Disclaimer: For estimation purposes only. Actual results depend on drivetrain losses, aerodynamics, and conditions.

Frequently Asked Questions