Whether you’ve been four-eyes-forever or a newbie to the specs world, getting the PD is probably something that gets most of us worked up. For sure, all of us want to save every penny and unfortunately, not many optical shops offer practical and affordable eyewear that most online stores offer. With the increasing number of stylish and inexpensive glasses sold online, you’ve probably tried scanning through catalogs and choosing a frame. Then you start typing in your Rx details but somehow, you couldn’t make it to the cart because of the PD that wasn’t included in your prescription.


Pupillary distance or PD is the measurement of the space between the pupils (the central black dots) of the eyes. This value is just as important as your standard prescription parameters as you would think. It determines where you look through the lens of your glasses and ensures that it matches with the optical center of your lenses. The average PD for adults ranges from 54-74 while PD values for kids usually stand within the 43-54 range. Getting the wrong PD on your eyeglasses prevents you from getting the correct optical center thus holding you back from that optimum vision eyeglasses were meant to provide.


So what is with this top secret PD that keeps us from getting a good deal online?


A lot of optometrists will not include your PD in your prescription simply because they don’t want you getting your glasses online. Online deals create competition because of the significant price difference—optical shops are far more expensive. While prescription nowadays can be acquired for free, not everyone will include your PD in it. In the United States, not all states require the inclusion of PD in the prescription without charge. In other states, unfortunately, getting your PD could be stressful than it’s supposed to be. Sometimes, a certain fee is required; sometimes, getting it is not an option.


Apart from marketing issues, eye care professionals (ECPs) may also not provide the PD because of accountability concerns. Possible problems in the manufacturing of the glasses may ultimately lead them liable for the problem, which shouldn’t be the case. According to the Federal Trade Commission, ECPs “are not liable under the Rules for the ophthalmic goods and services that another seller has dispensed”. However, it is their duty to release “truthful and non-misleading statements on prescriptions”.

How to measure pupillary distance is a common question among eyeglass wearers. Lots of consumers might overthink it, thinking that it needs a certain optometry tool or equipment to determine the PD. Here’s the good news: you can identify your PD even in the comforts of your home, making “How to measure PD at home?” the more appropriate question.

How to Measure Pupillary Distance on Your Own

  1. Stand 8-10 inches away from a mirror.
  2. Close your right eye then align the 0 mm of your pupillary distance ruler (millimeter side of the ruler) with the center of your left pupil.
  3. Look straight then close your left eye and open your right eye.
  4. The mm line that matches to the center of your left pupil is your PD.
  5. Repeat the procedure 3 times to ensure accuracy.

How to Measure Pupillary Distance with a Friend

Simply keep your eyes open. Have a friend hold the pupillary distance ruler and measure the distance from the center of your right pupil to the center of your left pupil.
Important notes to follow:

  • Keep your eyes as still as possible.
  • Have your friend crouch a little while you stand to clear off your field of vision.
  • Look above your friend’s head at a distance of around 10-20 ft.

Now that you’ve learned how to measure PD at home, you might notice that there’s an option to provide 2 PDs. Knowing which kind of glasses you’re getting greatly relies on how you want your glasses to serve your vision needs.


  • Single Vision – has a single power or focus over the entire lens; used for those who need glasses only for reading or driving
  • Bifocal/Progressive – has a range of vision correction within the entire lens

Getting your PD should never hold you back from exploring glasses selections online. Now that you’re equipped on how to measure PD at home, everything will come in easy. With your brand new knowledge on how to measure pupillary distance, you can now indulge yourself by purchasing that highly coveted glasses at Moonspecs.


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