How to Measure Your Pupillary Distance (PD) at Home

July 16, 2026

How to Measure Your Pupillary Distance (PD) at Home

Your pupillary distance (PD) is the space between the centers of your two pupils, measured in millimeters. It's essential for fitting new lenses correctly — but it's also the number most commonly missing from a written prescription, since many eye doctors don't include it unless you ask.

The good news: you can measure it accurately at home in about a minute, using nothing but a bank or ID card and a phone camera.

What you'll need

A bank card, ID card, or any card of standard size
A phone camera
A second person to take the photo (a steady hand matters more than you'd think)

Step-by-step instructions

Hold a card flat against your forehead, long edge horizontal, just above your eyebrows.
Take off your glasses. Have the other person step back 1–2 metres away, standing straight on at your eye level.
Look directly at the camera lens (not at the screen), keeping both eyes open, while they take the photo.

That's it — the card in the photo acts as a size reference, since its dimensions are standardized, which is what makes the measurement accurate without any special equipment.

What counts as a normal PD?

Most adult PD measurements fall between 48–76 mm. If a measurement comes out well outside that range, it usually means the card wasn't held flat or the photo wasn't taken straight-on — worth retaking rather than assuming it's correct.

Common questions

Do I need my PD for every type of lens?
Yes. It applies to single vision, bifocal, and progressive lenses alike — it's what ensures the optical center of each lens lines up correctly with your eyes.

What if my prescription already has a PD listed?
Great — use that number instead. It's typically more precise than a written prescription, but many prescriptions simply don't include it, which is when a home measurement helps.

Is a self-measured PD accurate enough?
It's accurate to roughly 0.5 mm using the card method above, and at lensfixers, a licensed optician double-checks every submitted measurement before any lens is cut — so there's a second check built in either way.