Pupillary Distance (PD) is the horizontal distance between your child’s pupils. Measured in millimeters, this distance is used to ensure that your child’s lenses are positioned correctly in front of your child’s eyes.

PD stands for Pupillary Distance; this is the measurement between the eyes from pupil to pupil measured in millimeters (mm). This measurement is an important part of the process of making prescription lenses to ensure the best possible vision.
Pupillary Distance can be expressed in two ways:
Binocular PD is the total distance between both of your pupils. Monocular PD is the distance from the bridge of your nose to your pupil on each side (A monocular PD measurement will be two numbers and should equal the same total distance of the Binocular measurement when added together)
Steps for measuring PD

  1. Print the PD Ruler to scale (see below)
  2. Facing directly across your child at eye level, hold the pupillary distance ruler at about arm’s length just below your child’s eyes.  Keeping it horizontal, align the ruler’s zero (0) measurement to the center of your child’s right eye pupil.
  3. Try your best to hold the ruler still and ask your child to hold as still as possible, and read the millimeter line that lines up with the center of your child’s left pupil. This is your child’s Binocular PD measurement.  
  4. Repeat the above steps at least three times to confirm your results.  
  5. The average kids Binocular PD ranges between 46mm and 60mm.
PD Taken by a Professional 
You can obtain the PD measurement from your child’s doctor’s office or go to a local vision professional to have them take the measurement.  This is part of standard eye care in our industry and there should be no charge for this service
PD Ruler Printout
In order to maintain the correct 100% scale of the PD ruler, save file to computer and open in Adobe Acrobat then print.