How to Measure Your Pupillary Distance

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 glasses prescription ensures 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.

1. Print our PD ruler. Print PD ruler at 100% size. Do not use 'scaling' or 'fit' setting. Print setting should be actual size. Measure against a millimeter ruler to assure printout is accurate.

2. Place the ruler directly over the center of your right pupil so that the ruler is horizontal. Place against forehead for added stability. Stand in front of a mirror, or ask someone else to measure for you.

3. While looking straight ahead, measure the distance from the center of your right pupil to the center of your left pupil.

4. Repeat a couple of times for accuracy and use an average for your final measurement.