Horsepower Calculator

Determines a ballpark estimate of horsepower

How to use

Enter an accurate (as possible) quarter mile time, Enter curb weight for the vehicle.


Most accurate results for flywheel horsepower depend on the accuracy of the user input using the true vehicle weight and 1/4 mile time for best results.


The resulting number is the engine horsepower at the flywheel which is the measurement car manufacturers claim. There is a loss of horsepower through drivetrain. Many sources say that you can expect at least a 15% loss of engine horsepower with front and rear wheel drive cars, more for all wheel drive vehicles. Efficiency is a major role in reducing drivetrain loss, many times what improves gas mileage also improves wheel horsepower through mechanical efficiency.

Did You Know?
Horsepower is a measure of performance based on the weight of coal one horse could pull. After extensive testing it was determined that one horse could pull approximately 33,000 pounds 1 foot in one minute, or 33,000ft-lb/min.
Brake Horsepower
Brake, sometimes called shaft horsepower, is the actual measurement of output from the engine including many components such as the gearbox. It is considered (about 10%) less than indicated horsepower (measured in frictionless combustion chambers) due to loss via heat & friction from within the engine itself.
The electrical equivalent of one horsepower is 746 watts (745.699872).