Belt Length Calculator (Fan Drives)
V-belt length from center distance and sheave sizes.
Enter your values
ⓘ Live results
Results
- Belt length (pitch)
- 70.2 in
- Nearest standard (round to 0.1)
- 70.2 in
- Wrap angle small sheave
- 170.4 deg
Quick answer
Belt length is approximately twice the center distance plus the average sheave circumference correction plus a diameter-difference term.
L = 2C + pi(D1+D2)/2 + (D2-D1)^2/(4C)
How to use the Belt Length Calculator (Fan Drives)
- 1Measure or set the center distance between shafts.
- 2Enter the small and large sheave diameters.
- 3Order the nearest standard belt length to the calculated pitch length.
Worked example
Using the values the calculator loads with:
Inputs
- Center distance24 in
- Small sheave diameter5 in
- Large sheave diameter9 in
Results
- Belt length (pitch)70.2 in
- Nearest standard (round to 0.1)70.2 in
- Wrap angle small sheave170.4 deg
Frequently asked questions
Why is wrap angle shown?
Wrap angle below about 120 degrees on the small sheave reduces torque capacity and belt life.
What if sheaves are the same size?
The diameter-difference term drops out and length is simply 2C + pi x D.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.