Belts & Pulleys
Pulley Wrap Angle Calculator
Estimate the contact angle around each pulley from pulley diameters and shaft center distance.
Inputs
Formula
Open-belt wrap angles
Worked example
Using the default values shown in the calculator, the same formula gives the following result. This is a quick sanity check for the calculation, not a design recommendation.
Inputs
- Large pulley diameter
- 250 mm
- Small pulley diameter
- 100 mm
- Center distance
- 500 mm
Result
- Small pulley wrap angle
- 162.75 deg
- Large pulley wrap angle
- 197.25 deg
Related calculators
Continue your workflow with a related calculation.
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Estimate pulley center distance from belt length and two pulley diameters.
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Frequently asked questions
Why is the small-pulley wrap angle important?
Less contact around the smaller pulley can reduce the available friction or tooth engagement, depending on belt type.
Does this apply to crossed belts?
No. These equations are for a two-pulley open-belt geometry.