What exactly is pupillary Distance?

Pupillary Distance (PD) is how far your pupils are separated. It is sometimes called inter-pupillary difference (iPD). PD can be measured as millimeters (mm) or as the measurement of a binocular or monocular. A single, or binocular reading is measured from one eye to the other. A monocular reading, also known as dual PD is the distance from the middle of one pupil to one's nose bridge. Two measurements are required two for each eye. They will add up to what is known as the total binocular PD reading.

PD may be measured at distance or close, depending on the position of the eye at the time of measurement. In the event that the patient focused on distant objects the distance PD is determined. In the case of a closer target, then near PD is recorded. If the distance isn't defined, one could suppose it is the case that PD is to measure distance.

The PD measurement is needed for the creation of an frame of spectacles. It tells the optician how to align the lenses within the frame to provide the most effective vision. The standard pupils of adults are 63 millimeters binocularly.

  • A majority of adult are binocular and have PDs ranging from 50-75 millimeters.
  • The single PD measurements vary from 41 to 55mm.

The PDs of children will alter as they get older. When an adult is mature, their PD will not change much in any way.

it yourself.

PD, also known as pupillary distance is the distance measured in millimeters from the center of one pupil and one's center. The proper PD on your prescription for glasses assures you that you're looking at the correct spot within your lenses. If this number wasn't included on the prescription of your eye doctor then you are able to measure it yourself.


1. The ruler should be placed directly over you right eye's center. Make sure you have a ruler that is horizontal. Set it on your forehead for extra security. Sit in the mirror or have someone else determine your measurements.

2. As you look straight ahead, count the distance between you right eye's center to your middle of your left pupil.

3. Repeat the process a few times to check for accuracy, and then take an average as the final measurement.


How can I determine my PD without using a ruler?

There are numerous applications for smartphones that analyze your PD by using the camera on your phone. You can locate the JubleeLens PD measure tool simply by hitting the 'i' key within the PD section while you enter your prescription.


Assess your PD based by yourself

Here's how you can measure pupillary distance yourself. You'll need an instrument with millimeter (mm) scales. Also, you'll need an mirror.

  1. Place yourself at about 8 inches (20 centimeters) away from the mirror
  2. Close your eyes to the left and gaze straight into the mirror.
  3. The ruler should be placed close to the right side of your eye. Then, measure what distance you can see between your bridge to the middle of your right pupil.
  4. Then, close your right eye and gaze straight into the mirror.
  5. Repeat the measurement to determine the pupillary distance left.

If you're looking for to measure your binoculars, you can add the left and right readings together. It is recommended to repeat the test many times (at minimum three times) to ensure the accuracy.