PD Meter for Glasses Pupillary Distance

Pupillary distance is the distance between the centers of your two pupils, measured in millimeters. Glasses lenses are centered on your pupils, so an online glasses store needs your PD to make lenses that line up with your eyes.

It needs a known size in the photo. A bank card is exactly 85.6 mm wide worldwide, so the tool compares the pixel distance between your pupils to the pixel width of the card and converts it to millimeters.

Close enough for ordering glasses, and the error comes from three places you control. The card sets the scale — every bank and ID card in the world is 85.6 mm wide, so that part is exact — but the card must be held in the same plane as your eyes; tilted, it reads shorter and the PD comes out too large. The camera should be roughly an arm away and level with your eyes, because a photo from below or above compresses the distance between them. And the marks are yours: place them on the pupil centers, not the iris edges. A result outside the usual adult range is flagged, which catches a slipped mark before it reaches your order.

Most adults have a PD between 54 and 74 mm, with around 63 mm being typical. Children's PD is smaller. The tool warns you if a reading falls outside the usual adult range.

This tool measures your total (binocular) PD, which most stores accept for everyday single-vision glasses. Some prescriptions use monocular PD — the distance from each pupil to the bridge of the nose — which an optician can provide.