Enter the PPR, great ratio, and the number of pulses received in 1 second into the calculator to determine the RPM.

PPR To RPM Formula

The following equation is used to calculate the RPM from PPR.

RPM = (Pulses Received in 1 Second)*60/PPR * GR

  • Where RPM is the rotations per minute
  • PPR is the pulses per revolution
  • GR is the gear ratio (X:1 i.e 13:1=13)

What is PPR?


Pulses Per Revolution (PPR) is a number that is used to describe the accuracy of some types of rotary encoders. An encoder is a device that converts mechanical motion into electrical signals. Rotary encoders are used as positioning systems in many applications, such as machine tools and robotics.

PPR measures the amount of pulses per revolution made by the encoder’s shaft. So, if a shaft has 100 PPR, then its encoder will produce 100 pulses every time it makes one full revolution. The more PPR an encoder has, the better its accuracy will be. This measurement is commonly used with incremental rotary encoders, which measure the distance an object travels in discrete increments.

For example, if a 100 PPR incremental rotary encoder is mounted on a motor and the motor turns through a full revolution, then that motor traveled 1 meter (or about 3 feet).

Incremental rotary encoders are used in situations where speed or position needs to be measured very precisely over time. In machine tools and robots, for example, high-resolution encoders can track small changes in position or speed very accurately over long periods of time

How to Calculate RPM from PPR?

Example Problem:

The following example outlines the steps and information needed to calculate RPM from PPR.

First, determine the pulses receives in 1 second. In this case, 4 pulses are received in one second.

Next, determine the PPR. The PPR for this example, is 50.

Next, determine the gear ratio. This gear ratio is measured to be 12:1 = 12.

Finally, calculate the RPM using the formula above:

RPM = (Pulses Received in 1 Second)*60/PPR * GR

RPM = 4*60/50 * 12

RPM = 57.6