Printable Pupillary Distance (PD) Ruler & Calculator

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Your pupillary distance (PD) is the distance between the centers of your pupils in millimeters — the one measurement you need to order glasses online that most prescriptions leave out. It tells the lab where to put the optical center of each lens, so you look through the sweet spot of the lens rather than its edge. Get it wrong and strong prescriptions in particular can feel strained and pulling.

This page gives you both halves of the job: a printable pupillary distance ruler at true 100% scale — with a calibration bar, because most printed PD rulers come out slightly undersized — and an online PD calculator to check the number you measured actually makes sense. Print the ruler, measure in a mirror, then check your result below.

1. Print the ruler

Print this page at 100% / "Actual size". Turn off "Fit to page" and any page scaling — a ruler printed at 94% will quietly hand you a wrong PD.

Check the print scale first

Measure this bar against any real ruler. It must be exactly 100 mm. If it isn't, your printer scaled the page — fix the setting and print again before measuring anything.

Your PD ruler

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Cut along the bottom edge so the millimeter marks sit right against your brow.

2. Measure

  1. Stand about 8 inches (20 cm) from a mirror, looking straight ahead.
  2. Hold the ruler flat against your brow, millimeter edge down.
  3. Close your right eye. Line up 0 mm with the center of your left pupil.
  4. Hold the ruler still. Now close your left eye, open your right.
  5. Read the mark over the center of your right pupil. That's your distance PD.

Repeat two or three times and average. For the full method — including dual PD, near PD and having someone measure for you — read the complete guide to measuring your PD.

3. Check your number

Is my PD plausible?

Most adults fall between 54 and 74 mm.

Single ↔ dual PD

Split evenly, each eye measures half. Faces aren't symmetrical, so a professional dual measurement is better for progressives.

Distance ↔ near PD

Near PD is roughly 3 mm less than distance PD — an approximation, not a substitute for a measured near PD.

Does my PD error actually matter?

If your lens sits off-center you look through a weak prism instead of the optical center. This is what causes that strained, pulling feeling — and how much it matters depends entirely on your prescription strength.

Enter both numbers to see the induced prism.

How that last one works. Opticians use Prentice's rule: induced prism (Δ) = decentration in centimeters × lens power in diopters. A 2 mm error on a ±4.00 lens gives 0.2 × 4 = 0.8Δ. As a rule of thumb most people tolerate up to about half a prism diopter without noticing; past that, symptoms get more likely — though sensitivity varies a lot between individuals.

Why not just use an online PD ruler on screen?

Because a screen has no fixed scale. The same image is a different physical size on a 13-inch laptop, a 27-inch monitor and a phone, and browser zoom shifts it again — so an on-screen ruler can be several millimeters out before you have even started measuring. Paper is the only surface you can verify: print it, measure the 100 mm calibration bar against something you trust, and you know your ruler is true. That is why the tool above is a printable pupillary distance ruler with a calibration check, and why the calculators stay online, where scale does not matter.

The same caution applies to card-and-phone-camera methods. They rely on a reference object of known width sitting in exactly the same plane as your pupils, which is difficult to hold accurately and easy to get wrong without noticing.

Ready to order

With your PD and your prescription you have everything you need. Not sure what the other numbers mean? Read how to read your eyeglass prescription. When you're ready, browse our eyeglasses — every Varadero optical frame is made prescription-ready for your own optician to glaze.

Built by Jarrett Johnson, a Florida-licensed, ABO- and NCLE-certified optician and the founder of Varadero. This tool is general information and a measuring aid — it is not a substitute for a professional measurement or an eye exam. For strong prescriptions or progressive lenses, have your PD measured by an optician.