Engine Horsepower Calculator
Calculate horsepower from torque and RPM
Enter Engine Specifications
Engine torque in pound-feet
Engine speed in revolutions per minute
Horsepower Result
About This Calculator
The Engine Horsepower Calculator helps you calculate engine horsepower from torque and RPM (revolutions per minute). Horsepower is a measure of engine power output and is essential for understanding engine performance.
This tool is useful for automotive enthusiasts, mechanics, and engineers who need to calculate or verify engine horsepower. The calculator uses the standard formula that relates horsepower to torque and engine speed.
Formula & Calculation Method
Horsepower is calculated using the formula:
HP = (Torque × RPM) / 5252
Where:
- HP = Horsepower
- Torque = Engine torque in pound-feet (lb-ft)
- RPM = Engine speed in revolutions per minute
- 5252 = Conversion constant (33,000 ft-lb/min / 2π)
Note: This formula assumes torque is measured in lb-ft (pound-feet). For metric units (Newton-meters), the formula is: HP = (Torque × RPM) / 7127, where torque is in N⋅m.
Key Insight: At 5,252 RPM, horsepower and torque are always equal. This is because 5,252 is where the two curves intersect on a dyno chart.
How to Use This Calculator
Frequently Asked Questions
What is horsepower?
Horsepower (HP) is a unit of power that measures the rate at which work is done. In automotive terms, it represents the engine's ability to perform work over time. One horsepower equals 550 foot-pounds per second or 33,000 foot-pounds per minute.
What is the relationship between torque and horsepower?
Horsepower is calculated from torque and RPM: HP = (Torque × RPM) / 5252. Torque measures rotational force, while horsepower measures how fast that force can be applied. High torque at low RPM provides acceleration, while high horsepower at high RPM provides top speed.
Why is 5,252 RPM significant?
At 5,252 RPM, horsepower and torque (in lb-ft) are always equal. This is a mathematical constant where the two curves intersect on a dyno chart. Below 5,252 RPM, torque is higher than horsepower; above 5,252 RPM, horsepower is higher than torque.
What is the difference between brake horsepower and wheel horsepower?
Brake horsepower (BHP) is measured at the engine's crankshaft, while wheel horsepower (WHP) is measured at the wheels after accounting for drivetrain losses. WHP is typically 15-20% lower than BHP due to losses in the transmission, differential, and drivetrain components.
NumCalculators Editorial Team
Multi-disciplinary Expert Team
The NumCalculators Editorial Team consists of subject matter experts across various fields who review and verify the accuracy of our calculators. Each calculator undergoes rigorous testing and validation before publication.