Using the Engine Horsepower Calculator
Enter the torque associated with the selected RPM. Combining maximum torque from one speed with a much higher speed from another point would create a power figure the engine may never produce. The result describes the entered operating point only.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Torque (N·m)
- 250
- Engine speed (RPM)
- 4000
Example result
- Mechanical horsepower
- 140.4315
- Power (kW)
- 104.71976
Method and assumptions
Power = torque × angular velocity. Uses mechanical horsepower, not metric PS.
Use torque and speed from one operating point
A power curve describes many operating points rather than a single universal output. Pair each torque reading with the rotational speed at which it was obtained. Repeat the calculation for other points if you want to compare them. Keep mechanical horsepower and kilowatts labeled, and avoid mixing engine-shaft measurements with wheel measurements.
Common question
Does the result predict acceleration?
No. Acceleration also depends on vehicle mass, gearing, traction and other conditions. The calculator converts torque and speed into power; it does not simulate a vehicle or estimate a quarter-mile time.
Guide updated .