Case 1
- Torque (lb-ft)
- 300lb-ft
- Engine speed (rpm)
- 5252rpm
300.00hp
Open with these valuesTorque to Horsepower Calculator
300.00hp
Result: 300.00 hpHorsepower is torque times engine speed divided by 5252: 400 lb-ft at 6000 rpm is 456.97 hp. The 5252 is not a measurement — it is 33000 ft-lbf per minute divided by 2π, so it works only with pound-feet and rpm. Enter newton-metres instead and the answer is wrong by a factor of 1.356.
The numbers at a glance
Held fixed: Torque (lb-ft) 300.00 lb-ft.
| Engine speed (rpm) (rpm) | Result (hp) |
|---|---|
| 2,000 | 114.24 |
| 4,000 | 228.48 |
| 5,252Your value | 300.00 |
| 6,000 | 342.73 |
| 8,000 | 456.97 |
| 10,000 | 571.21 |
Worked examples
Case 2
- Torque (lb-ft)
- 400lb-ft
- Engine speed (rpm)
- 6000rpm
456.97hp
Open with these valuesCase 3
- Torque (lb-ft)
- 200lb-ft
- Engine speed (rpm)
- 3000rpm
114.24hp
Open with these valuesHow it's calculated
hp = torque × rpm ÷ 5252
- StepRead the torque off the dyno chart in pound-feet, not newton-metres.
- StepRead the engine speed in revolutions per minute at that same point.
- StepMultiply the two and divide by 5252.
- ResultFor kilowatts multiply the result by 0.7457; for metric PS, by 1.0139.
Reference table
| Torque, rpm | Kilowatts (hp × 0.7457) | Mechanical horsepower |
|---|---|---|
| 100, 5252 | 74.57 kW | 100.00 |
| 200, 3000 | 85.19 kW | 114.24 |
| 300, 5252 | 223.71 kW | 300.00 |
| 350, 5500 | 273.32 kW | 366.53 |
| 400, 6000 | 340.76 kW | 456.97 |
| 500, 7000 | 496.94 kW | 666.41 |
Questions
How do I convert torque to horsepower?
Multiply the torque in pound-feet by the engine speed in rpm and divide by 5252. For 300 lb-ft at 5252 rpm that is 300 hp. The torque and the rpm must be read at the same point of the curve.
Why is the number 5252 used?
It is 33000 divided by 2π, and nothing more — one mechanical horsepower is defined as 33000 foot-pounds of work per minute, and one revolution is 2π radians. A neat side effect is that a torque curve in lb-ft and a power curve in hp always cross at 5252 rpm on a dyno chart.
Can I enter torque in newton-metres?
Not directly, because the 5252 assumes pound-feet. One lb-ft is about 1.356 Nm, so divide a newton-metre figure by 1.356 first. Skip that and the horsepower comes out too high by exactly that factor.
Is hp the same as metric PS?
No. The hp used here is mechanical horsepower, 745.7 watts, while the metric PS used across most of Europe is 735.5 watts. Multiply hp by 1.0139 to get PS, or by 0.7457 to get kilowatts.
What is the difference between torque and horsepower?
Torque is the twisting force the engine makes; horsepower is the rate at which that force does work. The same torque at higher rpm is more power, which is why a high-revving engine posts big horsepower from modest torque.
Sources and last check
Information, not professional advice.