Part of our Complete Guide to Buying Kids' Glasses
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Getting the fit right
PD: the one number that centers every lens
Pupillary distance is the gap between your child’s pupils in millimeters. Get it right and each lens sits perfectly in front of the eye — get it wrong and even a great frame feels off.
It takes about 60 seconds at home
All you need is a millimeter ruler and a mirror — or let our PD tool do it from a photo.
Just a rulerMeasured in mmOne quick readingFree PD tool
Measure it
Three easy steps
1
Face a mirror
Have your child look straight ahead at their own eyes, head level, about arm’s length from the mirror.
2
Rest a ruler on the bridge
Line the millimeter ruler across the bridge of the nose, just under the eyes, and hold it steady.
3
Read pupil to pupil
Measure from the center of one pupil to the center of the other. That number, in mm, is the PD.
Parent pro tip: take the reading two or three times and use the average — kids wiggle, and a steady number is more accurate.