🏎️ Horsepower Calculator
Convert between engine torque and horsepower with the classic HP = torque × RPM ÷ 5252 relation — go either direction by entering torque and RPM, or horsepower and RPM.
⚙️ Torque, RPM & Power
What is a Horsepower Calculator?
It applies the one equation that ties an engine's torque to its horsepower at a given engine speed. Torque is the twisting force the engine makes; horsepower is the rate at which it does work. Multiply torque by RPM, divide by 5252, and you have the power — which is exactly how a dyno turns a torque reading into the headline horsepower figure.
Use it to sanity-check a dyno sheet, estimate the torque behind a quoted horsepower number, or see why the two curves always cross at 5252 RPM. The conversion is exact, but the inputs are estimates — real figures vary by vehicle and how the engine was measured.
❓ Frequently Asked Questions
How is horsepower calculated from torque?
Engine horsepower is torque multiplied by engine speed, divided by the constant 5252: HP = torque (lb-ft) × RPM ÷ 5252. That single relation links the twisting force the engine makes at the crank to the power it delivers at a given RPM, which is why a dyno measures torque and computes horsepower from it.
Why do torque and horsepower curves always cross at 5252 RPM?
Because 5252 is the constant in the formula, plugging in 5252 RPM makes horsepower exactly equal to torque. Below that engine speed torque is the larger number; above it horsepower pulls ahead. The crossover is a mathematical certainty, not a property of any particular engine, so it shows up on every dyno chart.
Is this crank horsepower or wheel horsepower?
The formula gives whatever you feed it. If you enter crank (brake) torque you get crank horsepower; if you enter torque measured at the wheels you get wheel horsepower. Wheel figures are typically 10–20% lower than crank figures because of drivetrain losses through the transmission, differential, and tires.
How accurate are these numbers?
The conversion itself is exact, but the inputs are not. These are estimates for planning; actual figures vary by vehicle, how the engine was measured, dyno type and correction, temperature, fuel, and drivetrain losses. Use the result to compare setups, not as a certified output.