You might be asking, “PD? WTF?!?” PD, or pupillary distance, measures the space between the pupils of your eyes. This number is important when ordering prescription eyewear because it helps us ensure your eyes match up with the optical center of your lenses.

Your prescription may contain your PD measurement. If I doesn’t, just use our handy guide for measuring your PD at home.

Ready to measure? Click here for our handy guide.