Belt Length Calculator
Estimate the pitch-line length of an open belt running over two pulleys.
A QUICK WALKTHROUGH
How to use this tool
- Enter both pitch diameters and the centre distance in millimetres.
- Choose Calculate to see belt length and small-pulley wrap.
Formula and scope
L = 2C + π(R + r) + (R − r)²/C; wrap = 180° − 2 asin((R − r)/C), where R is the larger radius and r the smaller.
Scope
Approximation for an open belt and pitch-line length only. Select a standard manufacturer belt and allow for tension adjustment; pitch-line, inside and outside belt lengths can differ.
GOOD TO KNOW
Common questions
Is this an outside belt length?
No. This estimates the open-belt pitch-line length; inside and outside lengths can differ.