Beam angle calculator

This tool can help you determine the size of an optic needed for a given beam angle and LED chip including:

  • What size TIR lens is needed to create the beam angle I need?

  • What size reflector is needed to create the beam angle I want?

This calculator provides a rough estimate based on a etendue calculation. Enter the size of your LED chip (or select from one of the defaults we have entered) and the desired lens size to calculate the achievable beam angle. Please note that the estimate works for LEDs with a Lambertian beam angular profile; most LEDs produce a Lambertian beam.

If you need help developing a custom LED optic design, please let us know!

Calculate beam angle of TIR lens

Lens diameter, mm: LED source size, mm:

Beam angle calculator 1

FWHM or Full Width of beam angle profile measured at Half Maximum of luminous intensity center peak. A typical profile for TIR (Total Internal Reflection) lens is shown above. The example shows a beam half angle of around 7-8 degrees

Calculate beam angle of reflector

Reflector diameter, mm: Reflector height, mm: LED source size, mm: LED has round source shape

Beam angle calculator 2

Reflectors produce uncontrolled or ‘spill’ light around a main spot. A typical profile for a reflector is shown above. Compared to the TIR image, you will notice more light power at angles above the target angle.

How to measure LED source size

Beam angle calculator 3

How to measure size of round shaped LED source

Beam angle calculator 4

How to measure size of LED with square chip