What is a PD measurement?

PD, or pupillary distance, is simply
the distance between your child's pupils measured in millimetres.
It is an important measurement
that is used to customise their
prescription lenses.

How to measure your child’s Pupillary Distance

If you have obtained a prescription for your child, it may be written on that document. Alternatively, you can accurately measure your child’s PD at home using one of two different methods…


If your child already wears glasses a simple way to measure the PD is by marking a dot on their glasses with a non-permanent maker, and then measuring the distance between the two.
Step 1: Position yourself at eye level to your child. With your child looking straight ahead and their glasses on, cover one of their eyes with your hand and mark a dot on the glasses where their pupil is.
Step 2: Repeat step one for the opposite eye, ensuring you cover the eye you are not measuring.
Step 3: Taking a tape measure or ruler, measure the distance between the dots in millimetres. This is your child PD.
Step 4: Repeat these steps a few times to ensure accuracy.
An alternate way to measure your child PD is using a ruler ensuring your covering each eye as you align the ruler with the pupil.
Step 1: Standing at your child’s eye level, rest a ruler across your child’s brow line.
Step 2: With your child looking straight ahead, line up the 0 with the centre of one of their pupils.
Step 3: Record the number in the centre of their other pupil. This is their PD.
Step 4: Repeat these steps a few times to ensure accuracy.