How To Measure Your Pupillary Distance

Sep 13, 2021

pupillary distance measurement kit

What is pupillary distance?

Pupillary distance is the measurement taken in mm between the centre of your pupils. The measurement is unique to every person and it determines the optimum placement of vision in prescription lenses.

The Pupillary Distance also varies in size when you’re looking at long distance or close objects (long-sighted or short-sighted) and so the measurement plays a key part in the makeup of the lens. As every person’s face shape, eye placement and prescription needs are individual to them, it is vital that the measurement is taken correctly to ensure the lenses work in the correct way for the wearer.


How is pupillary distance measured?

Pupillary distance is measured in mm from the centre of the pupil straight across to the other eye’s pupil centre. Looking straight ahead, it’s a simple measurement that is crucial to ensure your lenses are their most effective, with the optical centre in the correct place as that is where our eyes naturally sit for most of the day. If you are wearing varifocal lenses, for example, the measurement is required so that the lens is designed correctly when factoring in its multifunctional purpose.


What is an average pupillary distance?

The average pupillary distance is between 54-74mm for adults and 43-58mm for children.

Take the measurement a few times when you are measuring yours or someone else’s to be sure you have a consistent result.

If you only take one and it’s a few millimeters out, the optical centre of your lenses will be off and your lenses won’t work effectively. Note also that if you have a particularly strong prescription, don’t rely solely on the average as a guesstimate, as an incorrect measurement can result in headaches, eye strain and further vision degradation.


How to measure your pupillary distance

At the opticians

If you are due to have an eye test, then you can request this information from your optometrist at the time of examination to add to your prescription. You know the funny glasses they put on you? That’s how they measure your pupillary distance, amongst other things. Some opticians however may either charge you for this information or refuse to provide it, potentially to keep glasses purchases in store. But if they do refuse, you can absolutely do it yourself.

Measuring yourself at home

There are several apps and tools online you can use on your smartphone or tablet to get your measurement. If you don’t fancy downloading more apps, however, you can easily measure yourself simply with a ruler or metal tape measure. Making sure the ruler is flat to the forehead and looking straight ahead, line up the 0mm mark with the centre of one pupil, then measure to the centre of the other. As mentioned, do this 3-4 times to get a consistent result and you’re set to complete your order.

Measuring someone else at home

The same rules apply, just make sure you are out of eyeline with the person you are measuring so as not to skew the measurement, children are particularly tempted to look at you instead! Where possible, have them look ahead to 10-20ft distance away and looking dead centre, with the ruler flat to their forehead.


If you don’t feel confident to do this yourself, we can help you.

Before posting your frames to us in your pre-paid postage box:
Take a picture of yourself wearing the glasses you want glazing so we can validate the image for Pupil Distance.

Ensuring your eyes are open and you are looking straight at the camera, don’t look up or down, or to the left or the right – straight ahead only. The image should be far enough away so we can check your head is in a natural position.

Once you have the perfect shot, send it to us at [email protected] stating your name, address, and postcode. Our friendly team will email you back and let you know that the picture is suitable. Then all you have to do is post your frames to us and we will do the rest.

Order your free postage box here and start your journey to clearer, better quality vision with Lensology.

Ready to order your FREE pack?

We provide a free postal pack that is delivered straight to your door, inclusive of a free return postage box for your frames. You’ll just need to provide a few simple details and then we can get it over to you ASAP!