Torque, Power and RPM Calculator
Find mechanical power from torque and speed.
Your numbers
Your results
Power (W)
Power (W)
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Power (kW)
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Power (mechanical hp)
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Torque (lb·ft)
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Torque, Power and RPM Calculator by TheCalcTools
How the Torque, Power and RPM Calculator works
Enter the torque in newton-metres and the shaft speed in revolutions per minute.
Angular speed in rad/s is rpm × 2π ÷ 60.
Power is torque times angular speed.
The formula
P = T × ωω = 2π × rpm ÷ 60
Worked example
Using the default values shown in the calculator:
| Torque (N·m) | 100 |
|---|---|
| Speed (rpm) | 3000 |
- ω = 3,000 × 2π ÷ 60 = 314.16 rad/s.
- P = 100 × 314.16 = 31,415.9 W = 31.42 kW.
- That equals 42.13 mechanical horsepower.
Result:
| Power (W) | 31,415.9 |
|---|---|
| Power (kW) | 31.416 |
| Power (mechanical hp) | 42.13 |
| Torque (lb·ft) | 73.76 |
Frequently asked questions
Why do engines list peak torque and peak power at different rpm?
Torque usually peaks at mid revs, then falls while power keeps rising until the engine runs out of breath.
What is the difference between metric and mechanical horsepower?
Mechanical hp is 745.7 W; metric hp (PS) is 735.5 W.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.