What is my pupillary distance and how to measure it?

What is my pupillary distance and how to measure it?
The pupillary distance (PD for short) is the distance between the centers of each pupil. We need this measurement so we can fit your lenses accurately. Sounds technical but it is a very easy measurement to take.
Note: In the UK this measurement is part of the dispensing service, remember to ask your optician!


The PD is the distance between the center of your right pupil and the center of your left pupil, measured in mm.

Note: If you are shopping in one of our stores, we will happily measure this for you in just a few short minutes free of charge.


Your PD measurement is normally included in your prescription from your optician, if not you can:

  1. Use one of many online tools to work out your PD measurements. These measurements aren’t always the most accurate, we advise you to try a few different ones to get the correct PD measurement.
  2. After completing your online order, send us a picture of your face with a bank card on your forehead and we’ll work it out for you. Don’t forget to quote your order number!
  3. Use one of the step-by-step guides below to measure your PD at home.

Measuring your PD at home for glasses wearers

  1. Wearing your current glasses, stand in front of a mirror and look straight into it.
  2. Close your right eye and, with a non-permanent marker pen, mark the center of the left pupil on the lens.
  3. Repeat the process with the left eye.
  4. With a ruler measure the distance between the two dots.
  5. You’ve got your PD! 

Measuring your PD at home for new glasses wearers

  1. Stand about 30cm away from a mirror.
  2. Hold a ruler against your browline.
  3. Close your right eye.
  4. Align the ruler’s 0 mm with the center of your left pupil.
  5. Look straight ahead.
  6. Close your left eye and open your right eye.
  7. The mm line that lines up to the center of your right pupil is your PD.
  8. You now have a single PD measurement! 
Tip: Repeat this exercise 3-4 times to get the most accurate measurement.

Note: Most people’s PD is somewhere between 58-68mm. If yours falls outside this, or you have a prescription over +/-6 SPH, get in touch with us and we’ll be happy to assist you. (link contacts)

Why is it important?

Your PD determines where your “optical center” lies and we need this measurement to glaze the lenses in your frame (link lab), this will help us make sure that you’re always looking through the correct part of the lens and that you’ll be seeing the world with the best possible vision. 

If your PD measurement isn’t correct, your new glasses could cause eye strain or not be effective in helping you to see properly. The higher your prescription, the bigger the chances of an incorrect PD affecting your glasses performance so don’t hesitate to get in touch(link contacts) with our Lab team for help!

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