Horsepower Calculator

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

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

Loading formula…
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
How to Use

About the Horsepower Calculator

What it calculates

This horsepower calculator computes engineering and applied physics quantities for circuits, fluids, and mechanical systems. Calculate engine HP from torque, performance, or convert power units.

When to use it

Use for coursework, lab estimates, and quick technical calculations.

Example

Adjust the inputs above to model your specific scenario with the Horsepower Calculator.

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