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Mechanical Engineering Calculators

Belt Length Calculator

Required belt length for a two-pulley drive from the diameters and centre distance.

Enter values

Results update as you type.

Result

Belt length

1,759.2 mm

In metres
1.7592
In inches
69.26
Wrap angle on the small pulley
165.64 °
Speed ratio
2.5 ×

About the Belt Length Calculator

Required belt length for a two-pulley drive from the diameters and centre distance.

Also known as: v belt length, pulley belt length, timing belt length, belt size calculator.

How to use this calculator

  1. Enter pulley 1 diameter, pulley 2 diameter, centre distance.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

L ≈ 2C + π(D₁ + D₂)/2 + (D₂ − D₁)² / 4C

Worked example

Using the values pre-filled in the calculator above:

  • Pulley 1 diameter = 100 mm
  • Pulley 2 diameter = 250 mm
  • Centre distance = 600 mm

the calculator returns:

  • Belt length: 1,759.2 mm
  • In metres: 1.7592
  • In inches: 69.26
  • Wrap angle on the small pulley: 165.64 °