How to Find Your PD for a GlassesUSA Order

Ordering prescription glasses from GlassesUSA means entering your pupillary distance along with the rest of your prescription. If the field caught you off guard, this walks through what PD is, where to find it, and how to measure it yourself if it's not written down anywhere.

What PD does

Pupillary distance is the distance in millimeters between the centers of your pupils. Lens labs use it to optically center each lens — to place the sweet spot of the correction exactly where your eyes look through. GlassesUSA stresses getting this as accurate as possible, because an off measurement can leave you looking through the wrong part of the lens even when the prescription itself is spot on.

Far PD vs. near PD

GlassesUSA points out that most people effectively have two PD values:

• Far PD — for distance vision. This is what's used for single-vision, progressive, and office lenses.
• Near PD — for close-range vision, used for bifocals and reading glasses.

And your two eyes don't have to match. The distance from each pupil to the bridge of your nose can differ slightly from one side to the other, which is why a dual (monocular) PD — two numbers — exists alongside the single (binocular) one. For multifocal orders in particular, both numbers matter.

As a rough plausibility check, GlassesUSA gives an adult range of about 55 to 75mm, and roughly 40 to 53mm for children. If your reading lands far outside that, it's worth measuring again.

Where to get your number

1. Your prescription. Eye doctors are supposed to list PD, but often don't. Worth a look first.
2. Ask the office. If it's missing, request it from whoever did your exam.
3. Measure it at home. GlassesUSA's own guide uses a mirror and a millimeter ruler: stand about 8 inches from the mirror, hold the ruler against your brow, and read the distance between your pupils by closing one eye at a time. Doing it with a friend tends to be steadier than doing it solo.

A no-ruler alternative

If you'd rather skip the ruler-and-mirror routine, our PD measurement tool reads the iris as a fixed-size reference through your camera, so there's no ruler to print or card to hold. You get a single and a dual number back — whichever one GlassesUSA's form asks for, it's ready to paste in. It's the same underlying idea as the camera tools the big retailers offer, just calibrated on the eye itself.

Keep it honest

Home measurement — whether by ruler, card, or camera — is a good estimate, not a clinical reading. For everyday single-vision glasses, being off by a millimeter rarely matters. For progressives, bifocals, or a strong prescription, measure a few times for consistency, and confirm against a professional measurement when you can. A little care here saves a return later.

Sources

• GlassesUSA.com Help Center — What is Pupillary Distance (PD)?
• GlassesUSA.com Help Center — How to measure your PD at home
• GlassesUSA.com Blog — 5 easy tips on how to measure pupillary distance