How to Measure your pupillary distance

If you wish to measure your own pupillary distance rather than use the optician standard then Specs2you® recommend you follow the following steps. (You can do this with a friend). Similarly, you could just use a mirror.

To measure the pupillary distance of another person, your friend should sit in a relaxed upright position (which feels as natural as possible). Then sit yourself directly in front of them facing them with about an arm’s length between you. The next step can be awkward as we are all different heights but it is important that you sit at eye-level with the friend, so an adjustable chair is preferable.

Once you are both in a comfortable position, you will need to determine which part of the eye you will use as a point to measure between. In the diagram below you can see that the pupil is clearly defined so it will be possible to measure in millimetres the distance between the centres of the pupils (as in figure 1).

Sometimes, the Iris of the eye can be darker making it harder to see the outline of the pupil. In this circumstance due to the natural symmetry of the eye, it’s possible to take a measurement from the outside edge of the iris on the right eye to the inside of the iris on the left eye or vice versa (as in figure 2).

To begin, hold the ruler at arm’s length resting in on your friend’s forehead, partially over their eyes. Close your right eye and ask your friend to look into your left eye using the index finger of your free hand to direct them to your open eye. Keep looking at their right eye and move the ruler so that the zero mark on the ruler is in line with the outside margin of the iris in the right eye. When confident that the ruler is in position, close your left eye and open your right while directing your friend to look into your open eye, moving your index finger across to aid their focus. Look into their left eye and read from the ruler in millimetres where the ruler lines up with the inside margin of the iris of the left eye (as in figure 3).

Specs2you® recommend you double-check this measurement! You will find on average that it is about 63mm but everyone is slightly different and measurements can vary between 50-75mm. If your prescription exceeds + or – 3 dioptres we strongly recommend that you carry out this measurement or ask your local optician to do it for you. There may be a small charge for this of approximately £15.00.