How To Measure Pupillary Distance

What Is Pupillary Distance?

Your PD is the distance between your eyes, measured between the centre of the pupils.

Learning how to measure Pupillary Distance (PD) is a simple measurement to help you order your new prescription glasses.



How To Measure Your Own Pupillary Distance


The Pupillary Distance is always measured in millimetres.

  • Stand around 8 inches away from a mirror.
  • Hold a ruler against your eyebrow.
  • Close your right eye then line up the ruler’s 0 mm with the centre of your left pupil.
  • Keep looking straight then close your left eye and open your right eye.
  • The mm measurement that lines up to the centre of your right pupil is your PD.

Adult’s PD's vary between 54-74 mm with average values for adults being approx. 63mm.

Can I get a friend to measure my PD?

Yes, here are some tips to help them.

  1. Sit directly infront of each other.
  2. Get a friend to rest a ruler on the bridge of your nose and centre the zero over the centre of one pupil.  It helps them to centre accurately by closing one eye, rest their index finger on their cheek while in their direct line of sight.
  3. You keep both eyes open at all times and focus on to the tip of their finger.
  4. They then switch eyes, to line up your other eye to read off the measurement, following the second step above.


Does my optician have to provide my PD?

No, so its always worth asking for, but if you forget, no problem.  Just follow the simple steps above.

Why Is Pupillary Distance Important?

All prescription lenses have an optical centre, which is used when making your glasses.

Having this information helps to customise the position of the lens so that you look through the optical centres when viewing normally into the distance.

Why is it important to look through the optical centre of the lens?

It eliminates prismatic effect when wearing glasses and ensures the most comfortable vision throughout the day.

What is the Mono PD?

Is the measurement of the centre of each pupil to the centre of the bridge of your nose.

In cases where the mono PD's are different, it is worth recording the right and left mono PD.

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