Printable PD Ruler (Pupil Distance Ruler)

Check the Print Before You Start

Printers often shrink pages a little so they fit the paper, and if that happens every measurement will be off. Set the print scale to 100% or "Actual size" and switch off "Fit to page" so the ruler prints at its real size.

There is a bank card outline on the sheet so you can check. Every bank or credit card measures 85.60 x 53.98 mm, so when you lay a card over the outline it should cover it perfectly. Another option is to place a real ruler next to the 50 mm line printed on the sheet. If either check fails, print the sheet again with scaling disabled.

What Is on the Sheet?

You get two rulers on the sheet to cut out, each marked in millimetres with numbers at every 5 mm. Ruler 1 begins at zero and measures a single PD, meaning the whole distance across between the centres of the two pupils.

Ruler 2 carries a mark at its centre that lines up with the middle of your nose, which lets a friend take a dual PD. A dual PD gives two figures, one per eye, and each one runs from the centre of the nose out to that pupil. Alongside the rulers, the sheet also has the card outline, a 50 mm reference line and brief instructions.

How to Measure PD With a Ruler

You can measure on your own with a mirror and the first ruler.

1. Stand facing a mirror and rest the ruler flat on your brow, level with your eyes.
2. Shut your right eye and set the zero mark over the middle of your left pupil.
3. Hold the ruler steady, shut your left eye and open your right one.
4. Note the mark under the middle of your right pupil; that figure is your single PD.

Having a friend do it tends to be steadier than using a mirror. Fix your gaze on something at the far side of the room while they set zero against one pupil and note the mark below the other one. If they use Ruler 2, they rest the centre mark on the middle of your nose and take a reading from each side.

Most adults measure between 50 and 70 mm, and 63 mm is typical. If your result sits well outside that span, it is worth measuring a second time.

Ruler Measurement Mistakes

The mistake people make most often is printing with scaling on, which leaves every millimetre on the ruler a touch too short or too long. Testing the sheet with a bank card before measuring will catch this.

Holding the ruler at an angle, or away from your brow, will also throw the number off. And if you look at the ruler rather than into the distance, your eyes turn inward, pulling the pupils nearer together and making the reading smaller.

A home measurement is an estimate, so if you can, ask your optician to check it.

PD Ruler Online: Can You Use One on a Screen?

Yes, the ruler can appear on a screen rather than on paper. Screens come in many sizes though, so the display first needs calibrating against an object of known size. You hold a bank card up to the screen and resize a box until it lines up with the card's long edge. From there, you follow the same measuring steps as you would with the paper version.