Enter the beam waist (mm) and the wavelength (mm) into the Calculator. The calculator will evaluate the Rayleigh Length.

## Rayleigh Length Formula

Zr = pi * w^2 / l

Variables:

- Zr is the Rayleigh Length (mm)
- w is the beam waist (mm)
- l is the wavelength (mm)

To calculate Rayleigh Length, multiply pi times the beam waist squared, then divide by the wavelength.

## How to Calculate Rayleigh Length?

The following steps outline how to calculate the Rayleigh Length.

- First, determine the beam waist (mm).
- Next, determine the wavelength (mm).
- Next, gather the formula from above = Zr = pi * w^2 / l.
- Finally, calculate the Rayleigh Length.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

beam waist (mm) = 80

wavelength (mm) = 90