Horsepower Calculator
Calculate horsepower from torque (lb-ft) and engine RPM.
- This Result300 hp
- Typical Passenger Car~200 hp
For scale, a typical modern passenger car makes roughly 200 hp — this result is about 1.5× that.
ƒShow your work
HP = torque × RPM ÷ 5252
- 1HP = 300 lb-ft × 5,252 RPM ÷ 5252 = 300 hp
- 25252 is the RPM at which torque (lb-ft) and horsepower always cross the same numeric value — it's not a rounding choice, it falls out of the unit conversion.
About the Horsepower Calculator
This calculator converts a torque and RPM reading into horsepower using the standard formula every dyno sheet and engine spec chart relies on. Torque and horsepower are related but distinct measurements, and this is the direct math connecting the two at any given engine speed.
It gets used by engine builders and car enthusiasts reading a dyno printout that only lists torque at a specific RPM, by anyone comparing spec sheets between engines that quote figures differently, or just out of curiosity about how a particular torque number translates into horsepower.
Because it's one formula applied to two numbers, everything computes instantly in your browser with no need to look up a conversion chart.
How it’s calculated
Horsepower equals torque (in lb-ft) multiplied by RPM, divided by the constant 5252. That constant isn't arbitrary — it falls directly out of the unit conversion between torque and power (horsepower is defined as work per unit time, and 5252 is the RPM value where the numeric torque and horsepower figures always come out equal, regardless of the engine).
That crossover point is why torque and horsepower curves on a dyno chart always intersect exactly at 5252 RPM — below that RPM, torque reads higher than horsepower, and above it, horsepower reads higher.
Frequently asked questions
Why do torque and horsepower always cross at 5252 RPM on a dyno chart?
It's a direct consequence of the formula itself — HP = torque × RPM ÷ 5252 forces the two curves to have identical numeric values whenever RPM equals 5252, no matter what engine is being measured. It's not a coincidence specific to any one engine.
Is horsepower or torque more important for performance?
They describe different things — torque is rotational force, horsepower is the rate of doing work over time (it factors in RPM). A high-revving engine can make strong horsepower with modest torque, while a low-revving diesel can make huge torque with modest horsepower; which matters more depends on the application.
Where do I find my engine's torque and RPM figures?
A dyno printout is the most accurate source, since it measures your specific engine rather than a factory average. Manufacturer spec sheets also list peak torque and the RPM it occurs at, though that's usually the single peak value rather than a full curve.
Does this calculator account for drivetrain losses?
No — this is the raw torque-to-horsepower conversion at the crankshaft (or wherever the torque was measured). Power measured at the wheels on a chassis dyno is typically lower due to drivetrain losses, and this formula doesn't adjust for that difference.
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