How to Measure Your PD

Pupillary distance (PD) is the distance between the centers of your pupils, measured in millimeters (mm). A correct PD measurement helps align the optical center of your lenses for clearer, more comfortable vision.

Printable PD Ruler

Print this page on A4 or US Letter paper using the 100% or Actual Size setting. To improve accuracy, take the measurement two or three times and calculate the average.

Download PD Ruler

What is Pupillary Distance?

Pupillary distance (PD) is the measurement between the centers of your pupils. It helps ensure that the optical centers of your prescription lenses are positioned correctly in the frame. Your eye care professional can measure it for you, or you can use our online digital PD ruler for a quick measurement.

Why Is PD Important?

Every prescription lens has an optical center designed to align with your pupils. An accurate PD measurement helps position this point correctly, providing clearer and more comfortable vision.

How to Measure Your PD at Home

Adult PD commonly falls between 54 mm and 78 mm. For a more reliable measurement, repeat the process 2–3 times and calculate the average of your readings.

Step 1

Stand approximately 8 inches (20 cm) away from a mirror. Keep your head straight and look directly ahead.

Step 2

Close your right eye and place the ruler so that the “0” mark is aligned with the center of your left pupil.

Step 3

Close your left eye, then note the millimeter mark that aligns with the center of your right pupil. This number is your total PD.

Step 4

For dual PD, measure the distance from the center of your nose to each pupil separately and enter the right-eye (OD) and left-eye (OS) measurements.

Single PD vs. Dual PD (OD/OS)

Select single PD when the checkout page provides only one PD field. If separate fields are shown for the right and left eyes, enter your dual PD measurements individually.

What Frame Size Is Right for Your PD?

Your PD helps determine which frame widths will place the lenses’ optical centers closest to your pupils for optimal comfort and clarity.