How to Measure PD

How to measure your pupillary distance by yourself?

PD (pupillary distance) is the distance from the center of the pupil in one eye to the center of the pupil in the other eye.

PD value is usually required when you fill in the prescription. Correct PD value ensures the correct centration of your prescription lenses in front of your eyes; otherwise one will feel fatigued, dizzy or sick. That is why PD is so important for you when getting a pair of prescription glasses.

The chart below shows the ordinary method of measuring PD by using a simple millimeter ruler.

Method A (Recommended): Use a vertical mirror and a ruler to measure by yourself.

Requirements: A friend, A smart phone or digital camera, A clear ruler (accuracy to mm) 

Keep the head vertical (to avoid the front and back) standing in front of the mirror, then put the ruler at the bottom edge of your eyes. Look at one eye (assuming the left eye) and align zero scale of the ruler with the center of left eye pupil. Then,

look at another eye(right eye), and check the scale of the ruler at the center of right eye pupil. Finally, if the scale is 65mm, then your PD is 65mm.

Method B: Use smart phone or digital camera

Requirements: A friend, A smart phone or digital camera, A clear ruler (accuracy to mm)

Sitting in front of your friend at least 2 meters away with your head upright (to avoid leaning front or back), and ask your friend to take a photo at the level of your eyes high. Zoom out the picture and read the distance from

 the center of the pupil in one eye to the center of the pupil in the other eye.