Belt Length and Pulley Speed
V-belt length, driven RPM, and belt speed from pulley diameters and centers.
Example
You enter
- Drive pulley diameter (in) 4
- Driven pulley diameter (in) 8
- Center distance (in) 18
- Motor RPM 1750
You get
- Belt length 55.07 in
- Driven RPM 875
- Belt speed 1832.6
Checked against published worked examples from: Bando USA.
Details, formula, and sources
Formula or tableV-belt length L = 2C + (π/2)(D + d) + (D − d)² / (4C). Driven RPM via diameter ratio. Belt speed (fpm) = π × d_drive × motor RPM / 12.
Source and editionGates / Goodyear / Bando manufacturer drive-design manuals by name.
Free accessFree at each manufacturer site.
What governsEstimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
API field namesdrive_dia_in, driven_dia_in, center_distance_in, motor_rpm, belt_length_in, driven_rpm, belt_speed_fpm