Complete Guide about PD ruler

PD ruler

Interpupillary distance, or “PD” for short, is an important measurement that you can need to offer to any eyewear supplier measuring ordering new eyewear. You’ll sometimes realize your PD on your official lens prescription, but don’t worry if you misplace it. 

What is the pupillary distance (PD)?

Simply put, the interpupillary distance is the distance from the center of the left pupil to the center of the right pupil. That makes sense, right?


PD ruler is typically measured in millimeters. To grant you a rough idea, an average adult has a pupillary distance between 54-74mm, whereas a child’s PD reading is typically between 43-58mm. But – everyone’s face is different! As an example, studies show that men tend to have slightly higher PD than ladies. 

Why is your PD important?

Knowing your PD is important because you wish to ensure you’ll see well from your brand-new glasses.

PD helps eyewear suppliers confirm the “ideal position” of your eyes in the eyeglasses. We use it to align your prescription to your pupils, ensuring your vision is clear and optimally corrected.

3 easy ways to induce PD

So now that you know what PD is, let’s find yours.


It’s very easy. Here are the 3 best ways to get PD:



  1. Read your PD directly from your lens prescription.
  2. Measure yourself with a ruler and mirror.
  3. Get an admirer to measure it for you.


How to browse your PD from your lens prescription

The most correct way to get PD is to envision the lens prescription you received from your ophthalmologist or specialist.


It’s also important to make sure you are checking your most recent lens prescription. Adult PD usually remains stable, but for still-growing children and adolescents, their PD will improve over time.


Single PD VS dual PD

Typically, pd ruler readings contain only 1 set of numbers. However, in some cases, two sets of numbers are given. In this case, the optometrist you’re visiting uses twin PD, which implies the pupillary distance is measured from the center of every pupil to the center of your nose.


Dual PD has a set of numbers for each eye, usually labeled “right” and “left.” In some cases, you’ll encounter OD and OS, which also means right eye and left eye.


How to measure PD yourself in three simple steps

If you cannot easily find your PD on your prescription (or if you cannot realize your prescription!), it’s very simple to measure yours at home.


To manually measure PD, you wish 2 things:



  • A ruler (preferably with millimeters)
  • A mirror


Step 1:

With a ruler in hand, stand about 8 inches from a well-lit mirror. Facing forward, looking straight ahead, place a ruler on your forehead above the bridge of your nose.


Step 2:

Next, close the right eye and align the beginning or “zero” of the ruler to the center of the left pupil. While keeping your eyes upright, open your right eye and close your left.


Step 3:

Now, open your right eye and you should be able to see numbers on the ruler aligned with the middle of the correct pupil. This is however you measure the pupillary distance.



The pupillary distance dimension does now no longer ought to be 100% to be useful, as it could tolerate a reasonably small margin of error. If you do measure your pupillary distance, it’s far recommended that you attempt several instances to make sure a fairly correct measurement.