Belt Drive Design Calculator

Driven-pulley speed and estimated belt length for a two-pulley open belt drive.

Driver pulley diameter d1 (mm)Driven pulley diameter d2 (mm)Driver speed n1 (rpm)Centre distance C (mm)Calculate

Equations

n2 = n1·d1/d2. Belt length L ≈ 2C + (π/2)(d1+d2) + (d2−d1)²/(4C).

Assumptions

Open flat/V-belt, no slip, standard two-pulley geometry — does not size belt cross-section or check power capacity.