How to Measure Your PD at Home

Your PD (pupillary distance) is the gap between the centres of your pupils in millimetres. It's essential for prescription glasses — it lines the optical centre of each lens up with your eyes — but it's often missing from prescription cards. Here are three reliable ways to get it.

1. Use our camera tool (fastest)

Every frame page on our site has a built-in camera PD tool. Click “Don't know your PD? Measure it with your camera” in the prescription step, allow camera access, hold your device at arm's length in good light, and look straight into the camera. The tool tracks your eyes and reads out a live measurement — typically accurate to within about 1mm — and drops it straight into the PD box. Everything is processed on your device; no video or photo is uploaded anywhere.

2. Ask wherever you had your sight test

Your PD is measured as part of dispensing glasses, and you're entitled to ask for it. If you've bought glasses in person before, a quick phone call usually gets it.

3. The ruler-and-mirror method

Stand about 20cm from a mirror with a millimetre ruler held flat against your brow. Close your right eye and line the ruler's zero up with the centre of your left pupil. Then — without moving the ruler — close your left eye, open your right, and read the millimetre mark at the centre of your right pupil. That's your PD. Repeat it two or three times and take the most common answer. A friend measuring for you (with you looking at a fixed point behind them) is even better.

What's normal?

Most adult PDs fall between 54 and 74mm. You might also see a “dual PD” written as two halves (e.g. 31/31) — one measurement per eye from the bridge of your nose. Our order form accepts either format.

A note on accuracy

For single vision lenses, being within a millimetre is comfortably fine. Our eyewear specialists sanity-check the PD on every order against your frame choice before it goes to the glazing lab — if something looks unusual, we'll contact you before anything is made.