Brake Horsepower Calculator
Calculated Engine Power
This is the power measured at the crankshaft.
What is Brake Horsepower (BHP)?
Brake Horsepower (BHP) is the measure of an engine's horsepower before the loss in power caused by the gearbox, alternator, differential, water pump, and other auxiliary components such as power steering pump and muffled exhaust system. It is the pure power output of the engine measured at the flywheel or crankshaft.
The Mathematical Formula
Calculating BHP involves the relationship between torque and rotational speed (RPM). The standard formula used in this calculator is:
BHP = (Torque × RPM) / 5252
The constant 5252 is a result of converting units of work into horsepower. Interestingly, on a dyno graph, horsepower and torque curves will always cross at exactly 5252 RPM because of this mathematical relationship.
How to Use This Calculator
To determine your engine's brake horsepower, you need two primary metrics: the peak torque (measured in pound-feet) and the engine speed at which that torque was achieved. Simply enter those values into the fields above and click calculate. This tool is essential for car enthusiasts, mechanics, and engine builders who want to verify the raw potential of an internal combustion engine.
Frequently Asked Questions
While often used interchangeably, HP (Horsepower) can refer to several different measurements. BHP specifically refers to the power at the flywheel (the "brake" refers to the type of dynamometer used to measure it). WHP (Wheel Horsepower), on the other hand, is the power that actually reaches the road, which is typically 10-20% lower due to drivetrain losses.
BHP gives you the most accurate representation of an engine's mechanical efficiency and output capacity independent of the vehicle's transmission or weight.
Yes, the relationship between torque and RPM remains constant across all rotational power sources, including electric motors and steam engines.