V-Belt Length Calculator

Inputs

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Use the same two-sheave geometry in either direction.
Use pitch / datum diameter, not outside diameter.
mm
Use pitch / datum diameter, not outside diameter.
mm
Distance between sheave centers.
mm
Optional: set to 0 if speed is not needed.
rpm

Results

Default result
Edit inputs
Belt pitch length (L)
1,363.8 mm
Pass

calculated pitch length

Also computed

Center distance (C) Pass 400 mm

known center distance

Small-sheave wrap (θₛ) Pass 158.4 °

comfortable wrap for a friction belt

Speed ratio (i) 2.5

reduction

Driven speed (n₂) 700 rpm

Belt speed (v) 9.163 m/s

Method notes 3 notes
  • Use pitch / datum sheave diameters. A V-belt rides below the outside rim, so OD usually gives a belt that is too long.
  • Open-drive length: L = 2C + (π/2)(D₁ + D₂) + (D₂ − D₁)²/(4C). Center distance is solved by the positive quadratic root.
  • Small-sheave wrap limits grip. If it drops below about 120°, reduce the ratio, increase center distance or add an idler.

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