Are the engine speed and wheel speed the same?

How to compare motors with torque, speed and power

The torque is the rotational equivalent of the force. A force accelerates things along a straight line, torque makes them rotate. It is given in Newton meters and the unit already makes it clear that torque is the product of a force (given in Newton) and its normal distance (in meters) to the axis of rotation. A force of 50 Newtons acting on a two-meter-long lever thus generates a torque of 100 Nm. The same applies to a force of 100 Newtons on a lever one meter in length. You get the idea.


An engine, regardless of whether it is a combustion engine or an e-machine, now provides torque at its output. However, the level of this torque is always more or less dependent on the speed. For this reason, the maximum torque is usually given as the speed at which it occurs.


Power is the product of force and the speed with which this force acts. If, for example, one assumes a load with a certain weight force, the power required for lifting the load quickly is greater than for lifting it slowly.

With the rotating output shaft of a motor, the power available at a certain speed is obtained by multiplying this speed by the torque applied at this speed.

Torque × speed = power

However, the units given in the usual performance diagrams do not really match each other. In order to really get to kilowatts, the product of the speed in revolutions per minute and the torque in Newton meters has to be divided by the factor 9550.

Convert PS to kW (and vice versa) you can quickly and easily with our online calculator.