How to measure v belts

Updated July 20, 2017

A V-belt connects an electric or gas motor to another device, and each device has a pulley for the belt. When the motor turns the pulley, the V-belt is also turned. The moving belt turns the pulley on the device which enables a function. Different devices have certain speeds for rotating. In order to determine this speed, the size of the pulleys and the distance between the devices needs to be configured. With these measurements, you can also accurately calculate the V-belt length.

Remove shrouds and pulley guards from the equipment to get access to the motor's pulleys and the device. Use a screwdriver or wrench to remove any screws or bolts.

Measure the distance between the centre of each of the two pulleys with a tape measure.

Use the tape measure again to determine the diameter of both pulleys.

Use the V-belt calculator, located in the Resources section, to find the V-belt's measurements.

Calculate the total length of the V-belt manually by using the following formula:

L = (π x (D + d)/2 + 2) x (l x cos(a) + a x (D -- d)/2).


Wear proper safety and protective equipment when working near an automotive engine. Be sure the engine is off when measuring.

Things You'll Need

  • Screwdriver or wrench
  • Tape measure
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About the Author

Elyse Gibbons started writing in 2006 as a contributing reporter for the "Press-Republican." In 2009 she became an interim managing editor for CNHI Publications, then returned to editorial writing in 2010 as a senior reporter for the "Malone Telegram." She holds a Bachelor of Arts in journalism from Plattsburgh State University.