Brake Horsepower (BHP) Calculator
Calculate your engine's true power output by entering the torque and the engine speed (RPM) at which that torque is produced.
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. It represents the actual amount of energy the engine generates and is measured using a brake-type dynamometer at the crankshaft.
The BHP Calculation Formula
The relationship between torque, RPM, and horsepower is mathematical. Because horsepower is a function of work done over time, we use the following standard formula:
The number 5,252 is a constant derived from the relationship between feet per minute and revolutions per minute. Interestingly, because of this math, torque and horsepower will always cross at exactly 5,252 RPM on any dyno graph.
BHP vs. HP: What is the Difference?
While "Horsepower" is a general term, "BHP" is more specific to the engine's output in isolation. In the United States, "HP" often refers to SAE Net Horsepower, which includes standard accessories. In contrast, BHP specifically focuses on the "brake" or friction applied to the crankshaft during testing.
Real-World Examples
| Vehicle Type | Torque (lb-ft) | RPM | Calculated BHP |
|---|---|---|---|
| Sport Compact | 258 | 6,000 | ~294 BHP |
| Heavy Duty Truck | 900 | 2,800 | ~480 BHP |
| High-Rev Racing Engine | 180 | 9,500 | ~325 BHP |
Why Knowing Your BHP Matters
Understanding your engine's BHP helps in tuning, performance modifications, and comparing vehicle potential. If you know your torque curve, you can identify the "Power Band"—the RPM range where your engine is most efficient and powerful. This is crucial for drag racing, towing, and even fuel economy.