Getting your glasses right
Measure your PD.
It takes two minutes.
Your PD (pupillary distance) is the measurement between the centres of your pupils. It tells us exactly where to position your lenses so everything you look through is perfectly aligned to your eyes.
Without it, even a technically perfect prescription can feel slightly off. With it, your glasses are made precisely for you.
Typical adult range
Step by step
All you need is a ruler
and a mirror.
Follow these four steps carefully and repeat the measurement twice to make sure you get the same number both times. That's your PD.
Get your ruler and mirror
You need a millimetre ruler and a mirror. Hold the ruler flat against your brow, parallel to your eyes.
Line up to your left pupil
Close your right eye. Align the ruler's zero to the centre of your left pupil, looking straight ahead.
Read from your right pupil
Close your left eye, open your right. Read the millimetre mark that lines up with the centre of your right pupil.
Repeat to confirm
Repeat the process twice more. If you get the same number each time, that's your PD. Write it down before ordering.
Can't measure it yourself?
Send us a photo.
We'll work it out.
Take a photo of yourself holding any standard credit card to your forehead. We can use the card as a reference to calculate your PD accurately. Email it to us with your order number and we'll confirm everything before we start making your glasses.
- 1 Make sure you're in a well-lit room with your glasses off.
- 2 Hold a standard credit or membership card flat against your forehead as shown.
- 3 Hold your camera at arm's length, level with your eyes.
- 4 Look at the camera lens, not the screen, when you take the photo.
Do I need a single or dual PD?
Most people have a single (binocular) PD, which is the total distance between both pupils. Occasionally an optician will give you two separate measurements (monocular PD), one for each eye. Both work fine. Just let us know which you have.
Can I find my PD on my prescription?
Sometimes, yes. Opticians aren't required to include it in the UK, so it's not always listed. If it is there, it'll appear as a number between 55 and 75, or as two numbers that add up to that range. If it's not there, just measure it yourself or ask us.
What if my PD is outside the normal range?
PDs outside 55 to 75mm are less common but not unusual. If you get a reading significantly outside that range, it's worth repeating the measurement or coming into a showroom so we can check it for you. We want to get it right.
Come into a showroom
Any of our team can measure your PD for you in under a minute. No appointment needed. While you're in, you can try on frames too.
Email us your photo
Send a photo to help@iolla.com with your order number and we'll calculate your PD and confirm before we start making your glasses.
Mon to Sat, 10am to 5pm