Belt Length Calculator (Two-Pulley System)

Your details

Outside diameter of the larger pulley. For a V-belt sheave, use the pitch diameter instead.
mm
Outside diameter of the smaller pulley. Must be smaller than or equal to the large pulley diameter.
mm
Distance between the centers of the two pulley axles. Must be greater than half the difference in diameters.
mm
Belt length (exact)
3,710.6mm

Total belt length using the exact trigonometric formula

Belt length (approx.)3,710.6mm
Straight-run length (each side)1,498.1mm
Wrap angle - large pulley185.7deg
Wrap angle - small pulley174.3deg
Arc contact - large pulley486.2mm
Arc contact - small pulley228.1mm
Arc contact - large pulley486.2
Arc contact - small pulley228.1
Straight-run (one side)1,498.1

Belt length: 3710.6 mm (center distance 1500 mm, pulleys 300 and 150 mm)

  • The exact belt length is 3710.6 mm. The engineering approximation gives 3710.6 mm, a difference of 0.00%.
  • The small pulley wrap angle is 174.3 degrees, which provides good contact for reliable power transmission.
  • The pulley diameter ratio is 2.00:1. The smaller pulley rotates 2.00 times faster than the larger one (assuming negligible belt slip).

Next stepThe approximation is within 0.00% of the exact value, suitable for most practical purposes. For final belt ordering, always use the exact value and add a small allowance for tensioning.

 = Powered by OnlyCalculators