What is pupillary distance (PD)?
The one measurement your optician may not hand over, and why your lenses need it.
The pupillary distance is the distance, measured in millimetres, between the pupils of your eyes — the centres of your eyes. It is sometimes also known as the distance PD.
An accurate PD measurement is required in order to make prescription glasses, and it is an essential part of your prescription. It tells us where to place the optical centre of each lens, so that you are looking through the right part of it.
Reading your PD
If your prescription has a single number for PD, somewhere in the range 50 to 70, you can enter it directly.
It may instead be shown as two numbers — a dual PD, such as 31.5 / 32. Here 31.5 is the right PD and 32 is the left, each measured from the centre of that pupil to the centre of the bridge of your nose.
If your PD is not on your prescription
You can measure it yourself, but we recommend contacting your optician and asking for the PD they recorded at your eye exam. It is the more accurate figure, especially for a stronger prescription.
Ready to measure yours?
Two minutes with a mirror and a ruler.
