Belt Length Calculator
Open-belt length for two pulleys from their diameters and centre distance, plus wrap angle on the small pulley.
Inputs
mm
mm
mm
Results
- Belt length
- 1,845 mm
- Belt length
- 72.64 in
- Wrap angle (small pulley)
- 160.8 °
Formula
L = 2C + π(D + d) ÷ 2 + (D − d)² ÷ (4C)
Wrap angle = 180° − 2·asin((D − d) ÷ 2C)
Assumptions & limits
- Open (uncrossed) belt drive.
- Use pitch diameters for V-belts; pick the nearest standard belt length and adjust tension.
Worked example
2×600 + π×400÷2 + 200²÷2400 = 1200 + 628.3 + 16.7 = 1,845 mm.