Horsepower Calculator
Last updated: June 2026 · Free · No sign-up required
Enter values above and click Calculate to see your result instantly.
Quick reference
Horsepower from torque at RPM:
| Torque (lb-ft) | 3000 rpm | 5000 rpm |
|---|---|---|
| 200 | 114 hp | 190 hp |
| 300 | 171 hp | 286 hp |
| 400 | 228 hp | 381 hp |
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Responsive design tested down to a 320px-wide phone screen. The input fields use native number/date keyboards on iOS and Android, the calculate button is thumb-sized, and the result still reads big and bold on the smallest screen. No app to download, ever.
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Interpretation guide
Horsepower facts:
| Concept | Detail |
|---|---|
| 1 hp | 550 ft-lb/s or ~746 watts |
| HP = TQ at 5252 rpm | Power and torque curves cross there |
| Crank vs wheel HP | Drivetrain loses ~10–20% |
| Trap-speed estimate | From weight and 1/4-mile speed |
Formula & methodology
Formula: HP = Torque(lb-ft) x RPM / 5252; trap estimate: HP = weight x (mph / 234)^3
Horsepower is the rate of doing work. The calculator derives it from rotational output using HP = torque x RPM / 5252, the constant that makes the two curves cross at 5252 rpm. It can also estimate engine power from vehicle weight and quarter-mile trap speed using Hale's formula. Remember that crank horsepower is higher than wheel horsepower because the drivetrain absorbs roughly 10–20% on the way to the tires.