Use this free engine horsepower calculator to solve horsepower, torque, or RPM with lb-ft or N m, then compare engine and wheel horsepower with an editable drivetrain-loss estimate.
300 lb-ft x 5252 rpm
Torque and RPM must be from the same point. Dyno standard, correction factor, drivetrain, temperature, tires, gear, and engine condition can change measured power.
Recent engine power calculations will appear here.
Torque, RPM, horsepower, and drivetrain estimates stay in this browser tab. Results are formula estimates, not dyno measurements.
Inputs and recent answers stay in this browser tab and are not sent to a server.
Calculate horsepower from lb-ft or N m torque and matching RPM.
Solve torque from horsepower and RPM in lb-ft or N m.
Solve RPM from horsepower and torque at one engine point.
Estimate engine horsepower from wheel horsepower and drivetrain loss.
Estimate wheel horsepower from engine horsepower and drivetrain loss.
Explain why horsepower cannot convert directly into vehicle speed.
About 300 hp and 255 whp
About 280.86 hp
262.61 lb-ft or 356.05 N m
About 5,252.11 rpm
About 300 engine hp
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Plain-language answers about when to use the tool, what it does with your inputs, what to double-check, and how privacy works.
Use it when your task matches one of these common needs: Calculate horsepower from lb-ft or N m torque and matching RPM. Solve torque from horsepower and RPM in lb-ft or N m. It works best when you already know two known torque, RPM, or horsepower values from the same engine point, or one engine/wheel horsepower value plus an editable drivetrain-loss estimate.
In plain language: Horsepower = torque in lb-ft x RPM / 5252.1131. Torque = horsepower x 5252.1131 / RPM. RPM = horsepower x 5252.1131 / torque in lb-ft. Wheel horsepower = engine horsepower x (1 - drivetrain loss). The examples on the page are there so you can compare your inputs with a torque, RPM, and wheel-horsepower example before copying the answer.
Torque: the twisting force at the exact RPM point you want to check. Choose pound-feet or newton-meters before calculating. RPM: the engine speed that matches the torque value. Horsepower rises only when torque is being applied at a specific speed. Horsepower: the known engine or wheel mechanical horsepower for a solve-for or drivetrain mode. It must match the other value on the curve. Drivetrain direction: whether the known value starts at the engine/crank or at the wheels. The reverse calculation divides wheel power by the remaining efficiency. Drivetrain loss %: an editable estimate of power lost before the wheels. It is not a universal preset for FWD, RWD, AWD, or a transmission type.
Read the headline answer, then check the smaller lines beside it. For everyday tools, those lines usually show the distance, time, cost, units, or setting that made the answer change.
This solves formula points and editable loss assumptions, not an engine-build prediction or certified dyno result. Real ratings depend on measured data, test standard, correction factor, gear, drivetrain, tires, and conditions. Check that torque, RPM, and horsepower describe the same point on the curve. Treat drivetrain loss as an assumption, and do not convert horsepower directly into km/h or engine displacement.
It can find horsepower from torque and RPM, torque from horsepower and RPM, or RPM from horsepower and torque. A separate mode estimates engine-to-wheel or wheel-to-engine horsepower from a loss percentage.
Yes. Choose N m in the torque-unit menu. The calculator converts N m to lb-ft for the horsepower equation and shows both torque units in the result.
Use Find torque. The calculator multiplies horsepower by 5252.1131, divides by RPM, and returns lb-ft and N m. Horsepower and RPM still need to describe the same engine point.
Use Find RPM. The calculator multiplies horsepower by 5252.1131 and divides by torque in lb-ft. This solves a formula point; it does not predict redline or a safe operating speed.
Choose Wheel hp to engine hp, enter the measured WHP and an estimated drivetrain-loss percentage, then calculate. The formula divides WHP by one minus the loss rate. The result stays an estimate because real loss is not fixed.
No. Transmission, oil, temperature, tires, gear, dyno type, speed, and test method can change the measured difference. Enter a percentage only when you have a reason to use it, and compare dyno results under consistent conditions.
No. Horsepower is power and km/h or mph is speed. Vehicle speed also depends on drag, rolling resistance, mass, gearing, tire size, traction, grade, and available power at that speed.
No. Displacement, compression, boost, airflow, fuel, heads, camshaft, exhaust, tuning, and RPM range interact. This page needs measured or supplied torque, RPM, horsepower, or wheel horsepower instead of guessing power from a parts list.
No. A dyno measures a real engine or vehicle under test conditions. This calculator solves formulas from values you enter, and the result can differ with correction factor, gear, temperature, tires, drivetrain, and dyno type.
The 5,252 constant comes from the relationship between pound-feet, RPM, and mechanical horsepower. With lb-ft and RPM, horsepower equals torque times RPM divided by about 5,252.1131.
No. The calculation runs in your browser tab. Your torque, RPM, horsepower, and drivetrain-loss entries are not sent to a server.