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Belt and Pulley Calculator

Find driven pulley speed, drive ratio, required belt length, belt speed and wrap angle for a two-pulley drive.

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mm
RPM
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mm
kW
Driven Pulley Speed

💡 Belt length is the theoretical pitch length — pick the nearest standard belt and adjust centre distance to suit. Keep wrap angle on the small pulley above about 120° to avoid slip, and belt speed under roughly 25 m/s for standard V-belts.