How to Measure Your Pupillary Distance (PD)

What is Pupillary Distance?

Pupillary distance (PD) measures the distance between the centers of your pupils. This measurement is used to determine where you look through the lens of your glasses and should be as accurate as possible. The average adult’s PD is between 54-74 mm; kids' are between 43-58 mm. Your eye doctor will usually measure your PD during an eye exam. However, if it was not given to you, the below 5 steps will help you measure it yourself.

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.

Armed with your PD and prescription, you can shop at Zenni to find your perfect pair of glasses.

How to Measure Your Pupillary Distance

What Is Pupillary Distance?

PUPILLARY DISTANCE (PD) measures the distance between the centers of your pupils. This measurement is used to determine where you look through the lens of your glasses and should be as accurate as possible.

The average adult’s PD is between 54-74 mm; kids' are between 43-58 mm.

PD = 62 mm

If you don’t have your PD from your eye doctor, you can measure it yourself with the help of a friend, as demonstrated in this quick HOW-TO-VIDEO, or you can measure it yourself with our step-by-step guide below.

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.

Measure the Distance

Your prescription may tell you your PD. But if the PD is not available, use your friend or a mirror to help you figure it out.

NECESSARY TOOLS:

MEASURING YOUR OWN PD

1 Stand 8 in. away from the mirror.

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

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

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

5 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

HAVING A FRIEND MEASURE YOUR PD

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.

TIPS WHEN A FRIEND IS MEASURING

  • Have them crouch/sit while you stand so 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!

What is Single vs Dual PD?

SINGLE PD is the pupillary distance between the center of one pupil to the other, which can be a distance PD or near PD. Distance PD can be used to order any type of prescription glasses except reading glasses. Read below to learn how to calculate near PD for reading glasses.

DUAL PD, or monocular PD, consists of two numbers and is the distance between the centers of each pupil to the bridge of the nose. Dual PD is usually written in the following notation: 33/31, where the left number is the left eye measurement and the right number is the right eye measurement.

How do you calculate near PD for reading glasses?

You can calculate Near PD for reading glasses by subtracting 3mm from your distance PD. For example, if your distance PD is 63mm, then your near PD is 60mm.

If you are using Dual PD to calculate near PD, then subtract 1.5mm from each eye’s measurement. For example, if your dual PD is 33/31mm then your near PD would be 31.5/29.5mm.