What Is PD And Why Is It Important?

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What is PD and why is it important?

Here at Zenni, we don’t think the confusion of how to properly measure your pupillary distance (PD) should stand between you and ordering fabulous new glasses and prescription sunglasses. Read on to see how easy it is to measure your PD right at home!

What is PD in Eye Prescription?

PD means “pupillary distance,” which is the distance between the center of each pupil. This measurement is used to determine where you look through the lens of your glasses. If the PD is wrong, or as we say in the optical world “out of tolerance,” you won’t be able to focus your eyes together properly. 


Singular vs Dual PD

Single PD Vs. Dual PD

A single PD is one number that represents the measurement of the center of one pupil to the center of the other in millimeters. The average adult PD range is between 54-74 mm. The average child PD range is between 43-58 mm.

A dual PD is provided with two numbers and represents the measurement of each pupil center to the center of the bridge of your nose in millimeters. An example of a dual PD measurement is 32/30. The first number corresponds to the right eye and second number to the left eye.

How to measure your PD

How to Measure Your PD At Home

Your eye doctor will usually measure your PD during an eye exam. If for some reason it wasn’t given to you, you can measure it at home using 4 simple steps and a ruler. If you don’t have a one on hand, you can print out Zenni’s PD ruler here.

  1. Stand 8 inches away from a mirror and hold a millimeter ruler against your brow.
  2. Close your right eye and align the 0 millimeter mark to the center of your left pupil.
  3. Look straight ahead and then close your left eye and open the right eye.
  4. The millimeter line that lines up to the center of your right pupil is your PD.

Need more visuals? Watch the video below to see how easy it is for you or a friend to measure your PD in the comfort of your home.

Now that you know your personal PD measurement, start shopping for your perfect frame from our wide selection of styles.

On a Budget? Shop our selection of cheap sunglasses. Priced cheaply not made cheaply.

Additional Resources For Finding The Perfect Frame 

Here are some other common topics that will help you select the right frame at Zenni:

If you still have questions, check out our Zenni Help Center or quick and easy answers!