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How to Measure Your Pupillary Distance (PD)

What is Pupillary Distance?

Pupillary distance (PD) measures the space between the pupils of your eyes. Knowing this measurement is important to make sure your eyes match up with the optical center of your lenses. The average adult’s PD is between 54-74; kids' are between 43-54.

How to Measure Your PD?

1.Stand 8 in. away from a mirror.

2.Hold a ruler 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.

Check out the graphic below for more information and to learn how your friend can help you measure your PD.

How to Measure Your
Pupillary Distance

What Is Pupillary Distance
Pupillary Distance (PD) is the measurement from the center of one pupil to the center of the other. If you are getting single vision reading glasses, use your near-vision PD, which is your distance vision PD lowered by 3 mm. PD = 62 mm
Why Is It Important?
Every set of prescription lenses has an “optical center,” which is determined by pupillary distance. Pupillary distance is used to determine where you look through the lens of your glasses and should be as accurate as possible. Optical Center
Measure The Distance
Your prescription may tell you your PD, but if the PD is not available. You can get your data with the help of your friend or a mirror. 

Stand 8 in. away from the mirror.


With your face straight, hold the ruler against your brow.


Close your right eye and align the ruler’s zero to the center of your left pupil.


While looking straight, close your left eye and open your right eye.


Read the mm line that lines up with the center of your right pupil. This number is your PD.

A Few Things to Note

Measure your PD 3-4 times to ensure it's accurate and consistent.

Range of Adult PD: 54-74 mm

Range of Child PD: 43-54 mm


If a friend is measuring your PD, keep both eyes open and have your friend put the zero on the millimeter ruler over the center of one pupil, then measure the distance to the center of the other pupil.


Have them crouch/sit while you stand so that they are out of your field of vision.

Look above his/her head at something approximately 10-20 ft. away.

Keep your eyes as still as possible.

Do not look at the person measuring!