One of the most common questions we answer at OFH is: 'What size lens do I need to create the needed beam angle?' Using the calculator below will give you a rough estimate. 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. Note that estimate works for LEDs with Lambertian beam angular profile. Most of LEDs produce Lambertian beam.