| Engine Speed | Horsepower |
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The Horsepower Formula
Horsepower is calculated from torque and engine speed: horsepower equals torque in pound-feet times RPM, divided by 5,252. Torque is the twisting force the engine produces, and horsepower is how quickly that force does work. Spin the same torque faster and you make more power.
Why 5,252 RPM Is Special
The number 5,252 comes from the math that links torque, rotational speed, and power. One consequence is that horsepower and torque are always numerically equal at 5,252 RPM. On any dyno graph, the torque and horsepower curves cross at exactly that engine speed — below it torque is the bigger number, above it horsepower pulls ahead.
Crank vs Wheel Horsepower
Manufacturers quote crank (flywheel) horsepower, but a dynamometer usually measures power at the wheels, after losses through the transmission, driveshaft, and differential. Front-wheel-drive cars lose around 10%, rear-wheel-drive around 15%, and all-wheel-drive 20% or more. The converter above translates between the two.
Torque vs Horsepower
Torque is what you feel pushing you back in the seat; horsepower determines top speed and how hard the car pulls at high RPM. A torque-rich engine feels strong off the line, while a high-revving engine makes its power up top. Both come from the same curve — this calculator just connects the dots.
Frequently Asked Questions
Is more torque or more horsepower better?
It depends on the goal. Torque wins for towing and low-end punch; horsepower wins for top-end speed. Most fast cars need plenty of both.
How do I find my torque?
Use a dyno, or work backward from a known horsepower figure: torque equals horsepower times 5,252 divided by RPM.
Why is peak horsepower at a higher RPM than peak torque?
Because horsepower depends on torque multiplied by RPM. Even as torque tapers off up high, the rising RPM keeps pushing power higher until the torque drop finally wins.