You've picked your frames, entered your prescription, and then the order form asks for your PD. You check your prescription and it isn't there. Don't worry: this is very common in the UK, and you can measure your PD at home in about two minutes.
What is pupillary distance (PD)?
Your pupillary distance is the distance between the centres of your two pupils, measured in millimetres. The lab uses it to place the optical centre of each lens directly in front of each pupil.
If your PD is wrong, you're looking through the wrong part of the lens. That can cause eye strain, headaches or blurry vision, especially with stronger prescriptions and varifocals.
Most adults have a PD between 54mm and 74mm, and the average is around 62–64mm. Children's PD is usually smaller, around 43–58mm.
Why isn't my PD on my prescription?
In the UK, PD isn't legally part of a glasses prescription. It's a measurement taken when glasses are fitted, so many opticians don't write it down. You can always ask your optician for it, but measuring it yourself works well for most single vision glasses.
Single PD vs dual PD
- Single PD is one number, the full distance between your pupils, for example 63.
- Dual PD (or monocular PD) is two numbers, measured from the centre of your nose to each pupil, for example 31.5 / 31.5 or 31 / 32. Right eye comes first.
Dual PD is more accurate because most faces aren't perfectly symmetrical. If you can, give us your dual PD. If you only have a single PD, that's fine for most prescriptions.
Distance PD vs near PD: reading glasses use a near PD, which is usually about 3mm less than your distance PD, because your eyes turn inwards slightly when you look at something close.
Method 1: Measure your PD with a ruler and a mirror
This is the quickest way to measure your PD on your own. You'll need a millimetre ruler and a mirror.
- Stand about 20cm (8 inches) in front of a mirror in good light.
- Hold the ruler flat against your brow, just above your eyes. Keep it straight and level.
- Close your right eye. Line up the 0mm mark with the centre of your left pupil.
- Without moving the ruler or your head, close your left eye and open your right eye.
- Read the millimetre mark that lines up with the centre of your right pupil. That number is your PD.
- Repeat three times and use the average.
Method 2: Ask a friend to measure it
This is more accurate, because your eyes aren't moving between readings.
- Sit facing your friend at the same eye level, about an arm's length apart.
- Look at a point in the distance over their shoulder, not at them. This gives your distance PD.
- Your friend holds a millimetre ruler against your brow and lines up 0mm with the centre of your right pupil.
- They read the mark that lines up with the centre of your left pupil.
- For dual PD, they also measure from the centre of the bridge of your nose to each pupil.
- Repeat two or three times and use the average.
Method 3: Use your old glasses
If you already have glasses that feel comfortable, an optician can measure the PD from them. You can also ask the optician who did your eye test. They often have your PD on file from your last fitting.
We can help too. Send us a message on WhatsApp and our team will help you get the right measurement before your lenses are made.
Tips for an accurate PD measurement
- Use a millimetre ruler, not a tape measure. Being 2mm out makes a difference.
- Keep your head still and the ruler level against your brow.
- Look into the distance for distance and everyday glasses. Look at something close only if you're measuring near PD for reading glasses.
- Measure several times. If your readings differ by more than 1–2mm, keep going until they're consistent.
- Get it done professionally for varifocals. Varifocals also need fitting heights, so an in-person measurement is best. Book a free eye test and ask for your PD while you're there.
Pupillary distance FAQs
What is a normal PD for adults? Most adults have a PD between 54mm and 74mm. The average is around 62–64mm, and men tend to measure slightly wider than women.
Does my PD change over time? For adults, PD stays the same throughout life. Children's PD increases as they grow, so it should be measured again with each new pair.
What happens if my PD is wrong? If your PD is a few millimetres out, you might notice eye strain, headaches or slightly blurred vision. The stronger your prescription, the more a wrong PD matters.
Can I order glasses online without my PD? You'll need it before your lenses are made. Measure it at home with one of the methods above, or contact our team on WhatsApp for help.
Is PD the same for glasses and sunglasses? Yes. Prescription sunglasses use the same distance PD as your everyday glasses.
Ready to order your glasses?
With your prescription and PD in hand, you have everything you need to order glasses online. If you're not sure what the numbers on your prescription mean, read our guide on how to read your glasses prescription.
Every order comes with a free home trial and 30-day free returns, and code VIP10 gives you 10% off.
