On your prescription

Learn what is PD and how to measure it
in this short video tutorial

PD or pupillary distance refers to the distance in millimeters between the center of one pupil to the center of the other. Having a correct PD on your prescription insures that you are looking through the ideal spot in your lenses. If this number was not provided on your prescription by your eye care professional, you can measure it yourself.

Learn more - How to read your prescription

Do it yourself!

  • Place a mm ruler directly under the center of your right or left pupil so that the ruler is horizontal. Stand in front of a mirror, or ask someone else to measure for you.
  • While looking straight ahead, measure the distance from the center of your left pupil to the center of your right pupil.
  • Repeat for accuracy.
Prescription example

Use an average

Note that the average PD is between 57 and 65mm, and an average of 62mm. For bifocal and progressive lenses, two PD values are needed. In these cases, EyeBuyDirect recommends getting your PD directly from your eye care professional.