Printable PD Ruler & PD Calculator

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Your pupillary distance (PD) is the distance between the centres of your pupils in millimetres — the one number you need to order glasses online that most prescriptions leave out. Print the ruler below, measure in a mirror, then use the calculator to check your result actually makes sense.

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 millimetre 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, millimetre edge down.
  3. Close your right eye. Line up 0 mm with the centre of your left pupil.
  4. Hold the ruler still. Now close your left eye, open your right.
  5. Read the mark over the centre 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-centre you look through a weak prism instead of the optical centre. 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 centimetres × lens power in dioptres. 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 dioptre without noticing; past that, symptoms get more likely — though sensitivity varies a lot between individuals.

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.