Enter the pitch diameter, rotational speed of the sheave, and the belt length into the calculator to determine the belt frequency.

Belt Frequency Formula

The following equation is used to calculate the Belt Frequency.

BF = pi*D*N/L 
  • Where BF is the belt frequency
  • D is the diameter of the sheave (in)
  • N is the rotational speed of the sheave (RPM)
  • L is the length of the belt (in)

To calculate the belt length, multiply the diameter by the RPM, then multiply by pi, then divide by the belt length.

What is a Belt Frequency?


A belt frequency is a rate at which a belt completes a full complete cycle of its length. In other words, it’s a measure of the time it takes to travel the full length of the belt.

How to Calculate Belt Frequency?

Example Problem:

The following example outlines the steps and information needed to calculate Belt Frequency.

First, determine the sheave diameter. In this example, the diameter is measured to be 5 inches.

Next, determine the RPM of the sheave. This is found to be 50 RPM.

Next, determine the belt length. This belt is measured to have a length of 36 inches.

Finally, calculate the belt frequency using the formula above:

BF = pi*D*N/L

BF = 3.14159*5*50/36

BF = 21.8165 belt lengths/min