PUPILLARY DISTANCE
Your pupillary distance (PD) is the distance between the centres of your pupils. It’s an essential measurement to ensure your lenses are positioned correctly for optimal vision.
You can usually request your PD from your optician or the store where you last purchased glasses. If you don’t have access to it, here are two easy methods to measure it yourself:
METHOD 1: MEASURE YOUR PD AT HOME WITH A RULER
You’ll need a mirror and a millimetre ruler.
  • Stand about 8–12 inches (20–30 cm) away from a mirror.
  • Hold the ruler just above your eyes, across your eyebrows.
  • Close your right eye and align the 0 mm mark with the centre of your left pupil.
  • Without moving the ruler, close your left eye and open your right eye.
  • Look straight ahead — the millimetre mark that aligns with the centre of your right pupil is your PD!

If you are unable to do it alone, a friend can help you using the following method:

  • Ask the person to focus on an object about 20 feet away, keeping both eyes open and looking straight ahead.
  • Hold a millimetre ruler across their brow. Position the 0 mm mark at the centre of one pupil.
  • Without blocking their vision, measure the distance to the centre of the other pupil.
  • Ensure they do not shift their gaze or look at you during the process — their eyes should remain steady.
  • Repeat the measurement several times to confirm accuracy.

For reference, the average adult PD typically ranges between 54–74 mm.

We’ll take care of adjusting your PD measurement if you wish to have reading glasses.

METHOD 2: USE A DIGITAL PD MEASURING APP
If you prefer a digital method, several smartphone apps can calculate your PD using your camera. We recommend:
  •  EyeMeasure – for iPhone users
  • GlassesOn – for Android/Samsung users
Just follow the app instructions and it will calculate your PD in a few quick steps.
Scroll down for more detailed information about pupillary distance, why it matters, and how to enter it correctly at checkout.

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FAQ's

Have questions? We’re here to help

What is Pupillary Distance?

Pupillary Distance (PD) is the measurement between the centres of your pupils. It helps ensure that your lenses are positioned correctly in front of your eyes for the best possible vision and comfort.

What is the Average Pupillary Distance?

On average, adult PD falls between 54mm and 74mm. For children, it’s usually between 43mm and 58mm. Keep in mind, everyone’s PD is unique — it’s always best to measure yours for an accurate fit..

Why is Pupillary Distance Measurement Important?

Your PD ensures that the optical centre of your lenses lines up with your pupils. This is key for clear, comfortable vision — especially with prescription lenses. The right PD helps prevent eye strain and makes sure you get the full benefit of your eyewear.

Can I monitor my cat's feeding behavior and patterns remotely with the cat feeder?

Can I use someone else’s PD for my glasses?

Is the cat feeder compatible with smart home integration?

Yes, many cat feeders are compatible with smart home systems such as Amazon Alexa or Google Assistant, allowing you to control feeding schedules and monitor your cat's feeding behavior using voice commands or smartphone apps.

What if I don’t know my PD? Can you help?

No worries! You can ask for your PD during your eye examination — opticians are entitled to provide this measurement to you. If you don’t have it, we also recommend some easy methods to measure it yourself at home. Click on this link to read about the different methods we recommend to get an accurate PD measurement.

Is Pupillary Distance different for each eye?

In most cases, the PD for both eyes is the same. However, sometimes the measurements can differ slightly, especially if you have muscle alignment issues like a squint (strabismus). In these cases, knowing the precise monocular PD — the distance from each pupil to the center of the nose — is important for accurate lens alignment.

Does PD change over time? Should I measure it regularly?

PD can change naturally due to aging and alterations in facial structure. While it remains fairly stable in adulthood, it changes a lot during childhood and adolescence, which is why regular measurements are essential for young people.

How accurate does my PD measurement need to be?

Accuracy is important! To ensure a consistent and accurate reading, repeat the measurement process a few times. This helps you confirm the PD and get the best fit and comfort from your glasses.

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