Horsepower ↔ Torque Calculator

The HP / Torque Relationship

Horsepower and torque are not independent measurements — they are linked by RPM through a fixed mathematical relationship. One is always derivable from the other if you know the engine speed.

The constant 5252 comes from converting units: one horsepower equals 33,000 ft·lbf/min, and there are 2π radians per revolution — dividing these yields 5252.11. At exactly 5252 RPM, horsepower and torque numbers are always identical on a dyno graph.

Torque vs HP — Which Matters More?

Torque does the work — it's the twisting force that accelerates the car. Horsepower is the rate at which that work is done. In practical terms:

• Torque determines how hard the car pulls out of a corner or off a dig, especially in the mid-range
• Horsepower determines how fast the car reaches top speed (since drag increases quadratically with speed, you need power to maintain high velocity)
• Turbo engines tend to peak torque early and hold it flat — wide, usable power bands. NA high-rev engines peak torque late and narrow but make power longer

SAE Net vs Gross

Modern ratings (post-2005) use SAE Net — power measured at the crankshaft with all accessories fitted (alternator, power steering pump, AC, etc.). Older "gross" ratings excluded accessories and often overstated output by 10–20%. Always specify when comparing.

Wheel HP vs Crank HP

Dynos measure at the wheels. Drivetrain losses (transmission, differential, axles) typically subtract 12–18% for RWD, 15–20% for AWD. A 400 WHP car is roughly 460–480 crank HP on a typical RWD platform.