How to Measure PD


How do I measure my Pupillary Distance (PD)?


PD or Pupillary Distance is the distance between the center of your pupils in millimeters (mm). It is an important measurement when purchasing prescription glasses online. PD is sometimes written on your prescription by your doctor. However, if you cannot find it, there is no need to worry. Simply follow one of the two easy ways below to measure your PD quickly.


PD Meter App by GlassifyMe

GlassifyMe's PD Meter App is available for both iOS and Android. All you need is a standard card with a magnetic strip (gift card, rewards cart, or points card) and you can measure your PD using the app in a few quick steps - without the need of a ruler. Our app uses advanced algorithms to ensure that your PD is calculated with precision.




Watch our video tutorial to learn how to use the app




PD Ruler

You can also measure your PD by using our PD ruler available here. To measure your PD:

  1. Download the PD Ruler (PDF file) and open it in Adobe Reader. Print it at No Scaling or 100% scale setting.
  2. Fold the PD ruler along the dotted lines.
  3. By looking in the mirror or with the help of a friend, line up the ruler's zero with your left pupil.
  4. Without moving your head or the ruler, mark the ruler where it lines up with your right pupil. This number is your PD.
  5. Enter your PD along with your prescription to complete your purchase.