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Engine Power, Torque, and RPM Tool

Horsepower Calculator

Calculate horsepower from torque and RPM, estimate torque from horsepower and RPM, and convert the result to watts or kilowatts for engine, motor, and car comparisons.

Torque, RPM, HP, Watts, and kW

Calculate Engine Horsepower

Use torque and RPM to calculate horsepower, or enter horsepower and RPM to estimate the torque required at that engine speed.

lb-ft
Torque slider
01200 lb-ft
rpm
Engine Speed slider
5009000 rpm
Formula: horsepower = torque in lb-ft x RPM / 5252. If you use Nm, the calculator converts Nm to lb-ft first.

Horsepower Formula

Horsepower is a power measurement. For engines measured with lb-ft torque, the common formula is horsepower = torque x RPM / 5252. The same formula can be rearranged to estimate torque from horsepower and RPM.

Torque vs Horsepower

Torque

Torque is twisting force. It helps explain pulling strength, launch feel, and how hard an engine can turn a shaft.

Horsepower

Horsepower combines torque and speed. It helps explain how quickly work can be done as RPM rises.

What Horsepower Means in a Car

More horsepower can help a car accelerate faster and maintain speed under load, but it is not the only factor. Vehicle weight, gearing, traction, torque curve, aerodynamics, and drivetrain losses also affect real performance.

Frequently Asked Questions

How do you calculate horsepower from torque and RPM?+

Use horsepower = torque in lb-ft x RPM / 5252. If torque is in Nm, convert Nm to lb-ft first, then apply the formula.

Why do horsepower and torque cross at 5252 RPM?+

Horsepower is derived from torque and RPM. With lb-ft torque, the math constant makes the numeric values equal at 5252 RPM.

What is the difference between horsepower and torque?+

Torque measures twisting force. Horsepower measures how quickly work is done, so it combines torque with engine speed.

What is good horsepower in a car?+

For everyday driving, many modern cars fall around 150 to 300 horsepower. Performance cars often exceed 350 horsepower.