How To Measure A Belt For A Motor. How to measure conveyor belt speed with encoders. Subtract 1/8 inch from the measurement and that gives you the length of belt needed to fit the distance you just measured.
Belt length = 2c + 1.57 x (d1 + d2) + 1” where Belt speed with 5 drive wheel. There is a good possibility most of the torque is being used to deform the belt, especially if the belt has any appreciable thickness.
If the width is 9 mm, you would need a 7 mm belt.
Measuring for a lathe belt is easy. That 5mm radius is a pretty sharp bend for all but a urethane film belt, a small bead chain, or a small roller chain. Bearing housings to measure the vibration levels. Use a cloth measuring tape (not a steel one) and wrap it around the outside of the belt.