Horsepower Calculator
Convert torque and RPM into horsepower.
Results update as you type.
How it works
Horsepower is the headline figure quoted for almost every engine, yet it is not measured directly; it is calculated from torque and engine speed, and this horsepower calculator does exactly that. Enter the torque your engine produces in pound-feet and the RPM at which it produces it, and the tool returns the corresponding horsepower using the industry-standard formula. The distinction between torque and horsepower confuses many drivers. Torque is the twisting force the crankshaft delivers, while horsepower describes how quickly that force can do work over time. Because power is force times rotational speed, the same torque produces more horsepower at higher RPM, which is why engines that rev freely often post big power numbers even with modest torque. Understanding this relationship helps you read a dyno graph, compare engines fairly, and appreciate why gearing lets a small high-revving engine feel quick. The math is grounded in physics rather than marketing. Multiplying torque in pound-feet by RPM and dividing by 5252 gives brake horsepower at that operating point, the same calculation used to turn dyno torque readings into the power curves you see in reviews. Enthusiasts tuning an engine, students learning mechanics, and shoppers comparing specifications can all use this calculator to move confidently between torque and horsepower at any engine speed.
hp = torque (lb-ft) × rpm ÷ 5252
Power is the rate at which work is done, and for a rotating engine that means torque multiplied by rotational speed. When torque is measured in pound-feet and speed in revolutions per minute, the constant 5252 converts the product into mechanical horsepower. That number arises from combining the definition of one horsepower, 33,000 foot-pounds per minute, with the 2π radians in each revolution, and it explains why torque and horsepower curves always cross at 5252 rpm on a dyno chart.
Source:Standard horsepower equation (torque × rpm ÷ 5252)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter torque and engine speed.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Horsepower updates instantly as you type — no button to press.
Frequently asked questions
Why is the number 5252 in the horsepower formula?
The constant 5252 comes from the definition of horsepower as 33,000 foot-pounds of work per minute combined with the 2π radians in one full revolution. Dividing 33,000 by 2π gives roughly 5252, the factor that converts torque in pound-feet at a given RPM into horsepower. It is also why every dyno chart shows the torque and horsepower curves crossing exactly at 5252 rpm.
What is the difference between torque and horsepower?
Torque is the rotational force an engine produces, felt as the shove that gets a vehicle moving, while horsepower measures how fast that force can perform work over time. Because power equals torque multiplied by rotational speed, a high-revving engine can make substantial horsepower from modest torque. Both matter: torque governs pulling and acceleration feel, horsepower governs top-end performance and sustained output.
Does this give crank or wheel horsepower?
The formula returns the horsepower at whatever point the torque was measured. If you enter crankshaft torque you get brake horsepower at the crank, the figure manufacturers quote. If you enter torque measured at the wheels on a chassis dyno, you get wheel horsepower, which is lower because the drivetrain absorbs some power. Be consistent about where your torque figure came from when interpreting the result.
Can I calculate torque if I know horsepower?
Yes, the relationship rearranges easily. Torque in pound-feet equals horsepower multiplied by 5252 and divided by RPM. This is useful when a specification lists peak horsepower and the RPM it occurs at but omits torque. Remember that peak horsepower and peak torque usually happen at different engine speeds, so the torque you calculate at the power peak is not the engine's maximum torque figure.
Why does horsepower keep rising as RPM climbs even when torque falls?
Because horsepower is torque multiplied by RPM, rising engine speed can more than offset a gradual drop in torque, so power keeps climbing past the torque peak. Eventually torque falls fast enough that horsepower peaks too, usually near the redline. This is why engines are geared to stay in their high-power band during hard acceleration, keeping RPM up where horsepower is greatest.