What is Pupillary Distance? Complete Guide to PD for Glasses

Pupillary distance (PD) is the distance in millimetres between the centres of your two pupils. It's one of the most important measurements in making prescription glasses — yet many people have never heard of it until they try to order glasses online.

Why Does Pupillary Distance Matter?

When an optician or lab makes your prescription glasses, they need to align the optical centre of each lens directly in front of your pupil. The optical centre is the point where the lens provides the most accurate vision correction. If the lenses are off-centre — even by just a few millimetres — you'll see through an incorrect part of the lens, leading to:

Blurry or distorted vision
Eye strain and headaches
Difficulty focusing, especially for reading
Dizziness or nausea with strong prescriptions

Types of Pupillary Distance

Binocular PD

The total distance between both pupils measured as a single number (e.g., 63mm). Used for most standard prescriptions.

Monocular PD

The distance from the centre of each pupil to the centre of the nose bridge, measured separately (e.g., L: 31mm, R: 32mm). Used for progressive lenses.

What is a Normal Pupillary Distance?

For adults, the typical PD range is 54mm to 74mm, with an average of around 63mm. There's no “right” or “wrong” PD — it simply reflects the width of your face and the spacing of your eyes.

61mm

Women (avg)

64mm

Men (avg)

48–56mm

Children

When Do You Need Your PD?

Ordering glasses online — virtually every retailer requires it
Progressive/bifocal lenses — monocular PD is essential
Strong prescriptions — accuracy matters more at higher powers
New frames — if your face shape has changed significantly

Can Your PD Change?

Once you reach adulthood (around age 18), your PD generally doesn't change. However, children's PDs increase as they grow, so measurements should be updated when ordering new glasses for kids.

How to Find Your Pupillary Distance

There are three main ways to get your PD:

Ask your optician — they measure it during your eye exam and should provide it on request
Use an online PD tool — like this one, using AI facial detection
Measure it manually — using a ruler and mirror (less accurate)

What is Pupillary Distance?