What is Pupillary Distance?

PD: Pupillary Distance is the distance between the centers of your pupils in millimeters. Having a correct PD on your glasses ensures that you are looking through the ideal spot in your lenses. It should be as accurate as possible. The average adult's single PD is between 55-75 mm; kids' is between 42-58 mm. If there is no PD on your prescription, you can check it with your doctor or measure it yourself.
One-number PD: If your PD consists of one number, also known as "Single PD", this is the pupillary distance between your pupils. This is typically your distance PD measurement, unless it is noted as a near/reading PD. The distance PD is usually between 40-80mm. You can also calculate near PD, used for reading glasses, by subtracting 3mm from your distance PD.
Two-number PD: If your PD consists of two numbers, also known as "Dual PD", this is the pupillary distance between the centers of each pupil to the bridge of the nose. It is written in the following notation: 32/30. The first number is the right eye, and second is the left eye. Both are less than 40.

How to Measure Your PD?

Step 1

Stand approximately 8 inches (20cm) away from a mirror.

Step 2

With your face straight, hold a ruler against your brow. Please measure your PD 3 times to get accurate results.

Step 3

Close your right eye and align the 0 mm over the center of your left pupil.

Step 4

Close your left eye, open your right eye, note the reading directly over your right pupil. That will be your Total PD.

Step 5

You also need to measure the distance from two pupils to the center of your nose respectively to make sure that if you have two PDs (OD & OS).

How to 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.