Horsepower Calculator
Work out engine horsepower from torque and rpm, from a quarter-mile time slip, or from a 0-60 time. Every result comes with kW, PS and an estimate of what reaches the wheels.
Press Calculate to print your slip
Estimate only. Real numbers vary with the dyno, the track and the day.
Got a power figure? See its 0-60 time
On this page
Five ways to find horsepower
Horsepower is easy to quote and hard to measure. This calculator gives you the honest options: the exact maths from torque and rpm, and estimates from what the car actually did, whether that's a quarter-mile time slip or a 0-60 run.
What you need
- Torque and rpm
- From a dyno sheet or a spec sheet, for the exact conversion.
- A time slip
- ET or trap speed from the strip, plus the weight of the car and driver.
- A 0-60 time
- From a stopwatch, a GPS app or a road test, plus curb weight and layout.
What you get
- Crank horsepower, plus the same figure in kW and PS
- An estimate of what reaches the wheels
- Torque from horsepower, at any rpm
- A cross-check: the quarter-mile or trap speed that power should deliver
hp, bhp, whp, kW and PS
Horsepower (hp)
One mechanical horsepower is 745.7 watts, or 33,000 foot-pounds of work per minute. It's the unit US and UK spec sheets use. More in what horsepower means. James Watt based the unit on a working horse, which can briefly make close to 15 hp.
Brake horsepower (bhp)
Power measured at the crankshaft on an engine dyno, before the gearbox. Manufacturer ratings are bhp, usually just written as hp.
Wheel horsepower (whp)
Power measured at the tires on a chassis dyno. Lower than crank power because the driveline takes 10 to 20 percent.
Kilowatts (kW)
The SI unit. 1 kW is 1.341 hp, so a 200 kW engine makes about 268 hp. Australia and much of Europe quote kW.
PS (metric horsepower)
735.5 watts, about 1.4% less than a mechanical horsepower. A 300 PS engine makes about 296 hp. Common on German and Japanese spec sheets.
Torque
Twisting force, in lb-ft or Nm. Power is torque multiplied by how fast the engine turns, which is why the two are linked by rpm.
Horsepower formula: how to calculate it by hand
With torque and rpm the formula is exact, and you can do it on a phone calculator. (For what the unit itself means, see what horsepower is.)
- Read the torque in lb-ft and the rpm it is measured at, from a dyno chart or a spec sheet.
- Multiply the torque by the rpm.
- Divide by 5,252. The answer is horsepower at that rpm.
From torque (lb-ft)
hp = torque × rpm ÷ 5,252
From torque (Nm)
kW = Nm × rpm ÷ 9,549
From quarter-mile ET
hp = W × (5.825 ÷ ET)3
From trap speed
hp = W × (mph ÷ 234)3
From a 0-60 time
hp = W ÷ (t ÷ (1.26 × D × G))1.695
- W
- Race weight (vehicle plus driver) for the time-slip formulas; curb weight for the 0-60 formula.
- D and G
- Drivetrain and gearbox launch factors, the same model the 0-60 calculator uses. RWD manual is 1.00.
- ET, mph, t
- Quarter-mile elapsed time, trap speed and 0-60 time, from a real run.
- Wheel horsepower
- Crank hp less a typical drivetrain loss: RWD 15%, FWD 12%, AWD 20%, motorcycles and EVs 10%.
Worked example: 300 lb-ft at 5,000 rpm is 300 × 5,000 ÷ 5,252 = 286 hp, which is 213 kW or 290 PS.
Real engine: the 2.4-liter engine in the Toyota GR86 and Subaru BRZ makes 184 lb-ft at 3,700 rpm, which is 184 × 3,700 ÷ 5,252 = 130 hp. Its 228 hp peak arrives at 7,000 rpm, where torque has fallen to about 171 lb-ft. Peak torque and peak power rarely happen at the same rpm.
Why 5,252?
One horsepower is 33,000 foot-pounds per minute. Torque in pound-feet acting through one revolution does 2π foot-pounds of work per pound-foot, and 33,000 divided by 2π is 5,252. That's why horsepower and torque curves always cross at 5,252 rpm on a dyno chart drawn in lb-ft: below that speed torque is the bigger number, above it horsepower is.
Need torque from a horsepower figure instead? The HP to Torque Calculator works it both ways, with real engine examples.
Horsepower from trap speed (most accurate at the strip)
Trap speed is how fast the car is going as it crosses the finish line, timed in a short speed trap just before the line. It depends mostly on how much power the car makes over the back half of the run, so a slow launch, wheelspin or a missed shift barely changes it. Elapsed time is different: every tenth lost at the start stays on the slip. That makes trap speed the better guide to horsepower.
Horsepower from trap speed
hp = W × (mph ÷ 234)3
- W
- Race weight in pounds: the car plus the driver.
- mph
- Quarter-mile trap speed. An eighth-mile speed is converted first (eighth-mile mph ÷ 0.8).
Worked example: a 4,117 lb race weight trapping at 114 mph gives 4,117 × (114 ÷ 234)3 = 476 hp.
- Include the driver. Leaving out 170 lb lowers the answer by about 5% for a typical car.
- The answer is crank horsepower. Take off a typical drivetrain loss for an estimate of wheel horsepower.
- Use the ET method for electric cars: as the examples below show, trap speed overstates them.
How to use it
Pick a method
Torque and rpm for the exact figure, or a time slip or 0-60 run for an estimate.
Enter what you have
Torque with its rpm, or weight plus ET, trap speed or 0-60 time. Switch units if your numbers are metric.
Set the layout
For the run-based methods, choose drivetrain and gearbox so the launch model matches your car.
Read the slip
Press Calculate. Compare methods: if trap speed and ET disagree, the launch is the difference.
Example calculations
| Input | Method | Horsepower | kW |
|---|---|---|---|
| 300 lb-ft at 5,000 rpmTypical V8 torque peak | Torque | 286 hp | 213 kW |
| 420 lb-ft at 4,000 rpmTurbo diesel or big V8 | Torque | 320 hp | 239 kW |
| 150 lb-ft at 8,500 rpmHigh-revving four-cylinder | Torque | 243 hp | 181 kW |
| 3,470 lb race weight, 13.17 sRWD manual | 1/4 mile ET | 300 hp | 224 kW |
| 3,470 lb race weight, 103.5 mphRWD manual | Trap speed | 300 hp | 224 kW |
| 3,300 lb curb weight, 5.2 sRWD manual | 0-60 time | 299 hp | 223 kW |
The three run-based rows describe the same 300 hp car, which is the point: the methods agree when the run was clean.
Worked examples with real cars
We ran six Car and Driver test results through this calculator: each car's curb weight plus a 170 lb driver, with the quarter-mile time and trap speed from the test. Here is what each method says, next to the maker's rating.
| Car (as tested) | Race weight | Time slip | From trap | From ET | Rated |
|---|---|---|---|---|---|
| Ford Mustang GT (2024, manual)Tested by Car and Driver | 4,117 lb | 12.5 s @ 114 mph | 476 hp | 417 hp | 486 hp |
| Honda Civic Type R (2023, manual)Tested by Car and Driver | 3,353 lb | 13.5 s @ 106 mph | 312 hp | 289 hp | 315 hp |
| Chevrolet Corvette Z06 (2023, dual-clutch)Tested by Car and Driver | 3,836 lb | 10.5 s @ 131 mph | 673 hp | 616 hp | 670 hp |
| Toyota GR Supra 3.0 (2021, automatic)Tested by Car and Driver | 3,517 lb | 12.1 s @ 117 mph | 440 hp | 407 hp | 382 hp |
| Volkswagen Golf GTI (2025, dual-clutch)Tested by Car and Driver | 3,463 lb | 14.2 s @ 100 mph | 270 hp | 241 hp | 241 hp |
| Tesla Model Y Performance (2026, electric)Tested by Car and Driver | 4,608 lb | 11.5 s @ 122 mph | 653 hp | 478 hp | 510 hp |
What the examples show. Trap speed landed within about 2% of the rating for the Mustang GT, Civic Type R and Corvette Z06, while the ET method came in 8 to 14% low on the same cars, because a launch and gear changes cost time but little trap speed. The Supra and GTI trap as if they make 12 to 15% more than their ratings. That fits the Supra: a Car and Driver dyno test measured 388 hp at the wheels from a 2021 Supra rated at 382 hp (see our WHP vs HP guide). The electric Model Y is the exception: trap speed overstates it by 28%, most likely because the formula was built from gasoline cars that lose time to gear changes, so the ET method is the better of the two for EVs.
Times from Car and Driver tests, which subtract a one-foot rollout. Hybrid and electric ratings are combined system power.
Sources and method
The torque method is exact: one horsepower is 33,000 foot-pounds per minute, which gives hp = lb-ft × rpm ÷ 5,252. The time-slip methods use Patrick Hale's formulas and the 0-60 method runs our 0-60 model in reverse, so treat those results as estimates.
- Britannica: the definition of horsepower (33,000 foot-pounds per minute)
- NIST Special Publication 811: unit conversion factors
- SAE J1349: the standard US carmakers use to rate net engine power
- Car and Driver tests used in the worked examples
Updated October 2026. Built and checked by the 0-60calc Team. Found a mistake? Tell us and we will check it against the source.
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Questions people ask
Is horsepower calculated from torque?
Yes, on a dyno that is exactly how it works: the dyno measures torque and rpm, and horsepower is torque multiplied by rpm and divided by 5,252 (with torque in lb-ft). Power is torque delivered at a rate.
What is trap speed?
Trap speed is the speed a car is doing as it crosses the finish line of a drag strip, timed in a short speed trap just before the line. It shows how much power the car makes more reliably than elapsed time, because a poor launch costs time but little speed at the finish.
Which is more accurate, horsepower from ET or from trap speed?
Trap speed. By the finish line the launch matters much less, so trap speed tracks power-to-weight closely. ET carries the launch, the 60-foot time and every shift, so wheelspin can make a powerful car look weak.
What weight should I enter?
For the time-slip methods, the vehicle as it ran plus the driver. For the 0-60 method, the curb weight without a driver, which is how published 0-60 times are usually measured. The calculator adds a 170 lb driver where the formula needs one.
Is hp the same as bhp?
In everyday use, yes. Brake horsepower means power measured at the crankshaft on an engine dyno, which is what manufacturers quote. Wheel horsepower, measured on a chassis dyno, is lower because of drivetrain loss.
What is PS, and why do European cars use it?
PS is metric horsepower, defined as 735.5 watts instead of 745.7. One PS is about 0.986 hp, so a 300 PS engine makes roughly 296 hp. Many European spec sheets quote PS or kW.
Can I calculate horsepower without a dyno?
You can estimate it. A time slip or a stopwatch 0-60 time plus an accurate weight gives a useful ballpark, usually within a few percent for a well-launched run. A dyno is still the only way to measure it.