How to Measure PD

PD, or Pupillary Distance, is a term that describes the distance between the centers of your pupils. This measurement must be as accurate as possible as it indicates where a person looks through the lens of their glasses, which is known as the optical center. PD is usually measured by an eye doctor during an exam. However, if you are trying to purchase glasses without a prior eye exam, we have outlined some simple steps to help you measure it yourself.


  1. Stand 8 inches away from a mirror.

  2. Hold a ruler that measures in millimeters against your brow.

  3. Close your right eye, then align the ruler’s 0 mm with the center of your left pupil.

  4. Look straight, then close your left eye and open your right eye.

  5. The mm line that lines up to the center of your right pupil is your PD.

It is recommended that you undergo these steps at least 3-4 times to insure accuracy and consistency. For reference, the average range of an adult’s PD is 54-74 millimeters, while the average range of a child’s PD is 43-58 millimeters.