Measuring your pupillary distance shouldn’t be complicated.

Your PD helps us position your lenses correctly.

This guide shows you how to measure it accurately at home.

What is pupillary distance?

Pupillary distance—usually shortened to PD—is the distance between the centres of your pupils, measured in millimetres.

It helps us align the optical centre of each lens with your eyes, so your glasses provide clear and comfortable vision.

Your PD is a dispensing measurement, so it may not appear on your glasses prescription.

What you’ll need

Measuring your PD at home only takes a few minutes. You’ll need:

  • A ruler marked in millimetres
  • A mirror
  • Good, even lighting

For the best result, keep your head straight and measure three times.

How to measure your PD

Step 1: Get into position

Stand around 20 cm from a mirror. Look straight ahead and hold the ruler level across the bridge of your nose.

Step 2: Align the ruler

Close your right eye and line up the 0 mm mark with the centre of your left pupil.

Step 3: Take the measurement

Without moving the ruler, open your right eye and close your left. Read the number aligned with the centre of your right pupil. This is your PD.

Step 4: Check it again

Repeat three times and use the most consistent result. If the measurements vary, ask someone to help.

Single and dual PD

A single PD is one total measurement, such as 63 mm.

A dual PD gives a separate measurement for each eye, such as 31 mm / 32 mm.

If your optician has provided your PD, enter it exactly as written.

Before submitting

Make sure the ruler was level, you measured in millimetres and you repeated the measurement three times. Avoid guessing.

Not sure about your PD?

We’re here to help.

If your measurements keep changing or you’re unsure which number to enter, don’t guess. Contact us before completing your order and our optical team will guide you.

Optician-led always

Every prescription at OpticalGlasses is reviewed with clarity, comfort, and everyday wear in mind.

If something doesn’t feel right once your glasses arrive, we’ll help you check the details and get things corrected.

You shouldn’t have to guess — and you won’t be left on your own.