Ask The Optician | Optical Centre Smarbuyglasses UK

What Is PD on Glasses?

What does PD mean for glasses? Let’s find out.

Your pupillary distance (PD) is the distance between your pupils. It determines comfort, lens alignment and how well your glasses fit. Having your PD handy is just as essential as your prescription when it comes to ordering a new pair of eyeglasses or prescription sunglasses online.


The average pupillary distance for an adult is about 63 mm, but this is not a number you’ll want to guess at. After all, measurement can vary; it’s usually between 51mm and 74.5mm for women and 53mm and 77mm for men, but your own PD will be unique to you.

There are two different PD measurements: single PD and dual PD. 

  • Single PD (or binocular PD) is the measurement from pupil to pupil between each eye. 

  • Dual PD (or monocular PD) is the measurement from your nose bridge to each eye. 


Dual PD is believed to be the most accurate since many people may find their nose-to-pupil measurement is not equidistant on both sides. PD is very important when fitting glasses with progressive lenses, as these require precise lens-to-pupil alignment in order to ensure comfortable vision at all distances.


How to Find Pupillary Distance With a Friend  

Step 1: Your pupillary distance ruler can be any millimetre ruler. Hold this ruler up to the bridge of your nose.

Step 2: Have a friend stand about an arm’s length away from you, or face a mirror.

Step 3: Close your right eye and ensure the pupillary distance ruler’s zero point is aligned with your left pupil looking in the mirror or asking a friend. 

Step 4: Keeping the pupillary distance ruler still, look straight ahead. Close your left eye and open your right eye.

Step 5: Read the number that aligned with the center of your right pupil. This number is your pupillary distance.

Step 6: Repeat the process to ensure the most accurate result.​​​​ Coupons on