Enter each pulley’s diameters and the length between them into the calculator below to determine the belt length.

## Belt Length Formula

The following formula is used by the calculator above to calculate the belt length in a two-pulley system.

BL = ((D_{L} + D_{S}) * π / 2) + (2 * L) + (D_{L} – D_{S})^{2} / (4 * L)

- Where BL is the belt length
- DL is the diameter of the larger pulley
- DS is the diameter of the smaller pulley
- L is the distance between pulleys (center to center)

It’s important to keep in mind that the belt length will be in the same units of measure as the pulley diameters. For example, if both the smaller and larger pulley diameter is measured in inches, the belt length will also be inches.

## Belt Length Definition

A belt length is defined as the total length of material required to wrap around and between two different pulleys.

## How to calculate a belt length?

How to calculate belt length

**First, determine the diameter of the larger pulley.**Measure the diameter of the larger pulley.

**Next, determine the diameter of the smaller pulley.**Measure the diameter of the smaller pully.

**Next, measure the distance between pulleys.**This is the distance between the centers of the pulleys.

**Finally, calculate the belt length.**Using the formula above, calculate the belt length.

## FAQ

**What is a belt length?**

A belt length is defined as the total length of material required to wrap around and between two different pulleys.