Horsepower Calculator
Calculate horsepower, kilowatts and PS from torque in Nm or lb-ft and engine speed in rpm.
Horsepower
126.39 hp
Mechanical horsepower at this speed
Kilowatts
94.25 kW
Metric horsepower
124.66 PS
Power = torque × speed ÷ 5,252 (lb-ft) or ÷ 7,120.77 (Nm). This is the power at a single engine speed — peak horsepower usually sits higher up the rev range.
Last updated: January 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Use this calculator when comparing bikes and cars from their torque curves, or when reading a dyno graph after an upgrade like a remap, exhaust or turbo kit. Indian owners often know their machine's torque figure but not what it means in power — this converts it directly. It also helps in engineering coursework, where torque-speed-power problems are a staple of mechanics exams, and in workshops estimating whether an engine swap or pulley change will deliver the expected gain. The kW readout is handy for generator and pump specifications, which are rated in kilowatts, and for electric motor selections where power and speed determine the unit's rating. Punch in the numbers from any spec sheet and you can compare machines across units.
How to Use This Calculator
- Step 1: Find the engine's torque figure from the owner's manual, dealer brochure or a dyno sheet.
- Step 2: Choose the torque unit — Nm is standard in India; lb-ft appears on imported bikes and older manuals.
- Step 3: Enter the engine speed in rpm where that torque applies.
- Step 4: Read horsepower, kilowatts and PS at that engine speed.
Worked Example
A motorcycle engine producing 250 Nm at 4,500 rpm makes 250 × 4,500 ÷ 7,120.77 = 157.99 hp, about 117.81 kW or 155.8 PS. The same engine at 3,000 rpm with 300 Nm makes 126.39 hp — higher torque but lower power, because power multiplies torque by speed. This shows why peak torque and peak power almost never occur at the same rpm on a dyno chart.
Tips and Common Mistakes
- •Use the torque at the rpm you care about — quoting peak torque with peak-rpm power mixes two different engine states.
- •Check whether the brochure quotes wheel power or flywheel power; drivetrain losses run 10–15%.
- •For electric vehicles, kW from this calculator compares directly with motor output in the spec sheet.
- ✗Do not mix units — entering Nm torque into the lb-ft formula divides by the wrong constant.
- ✗Do not treat this as the vehicle's maximum horsepower unless your torque and rpm are both at the peak-power point.
Frequently Asked Questions
How is horsepower calculated from torque?
Horsepower = torque × rpm ÷ 5,252 when torque is in lb-ft, or ÷ 7,120.77 when it is in Nm. For example, 300 Nm at 3,000 rpm gives 126.4 hp. Power is the rate of doing work; torque is the twisting force.
What is the difference between hp, kW and PS?
They are the same quantity in different units: 1 hp = 0.7457 kW = 0.98632 PS (metric horsepower). Indian vehicle brochures commonly quote both bhp and kW; this calculator shows all three.
Why does peak torque and peak power occur at different rpm?
Power = torque × speed, so even if torque falls at high rpm, power can keep climbing. Peak power usually appears higher in the rev range than peak torque — check your car's dyno chart for the numbers.
Is this the same as brake horsepower (bhp)?
Mechanical horsepower measured at the flywheel is usually what manufacturers call bhp. This calculator returns the theoretical power from torque and rpm, which matches flywheel figures before drivetrain losses.
Can I calculate my car's power without a dyno?
Roughly, yes — find the torque curve from the manufacturer or owner forums and enter torque at the rpm you care about. Real-world wheel power is typically 10–15% lower due to transmission losses.
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