Why Won't My Optician Give Me My PD?

If you've just picked up a copy of your glasses prescription and noticed there's no pupillary distance (PD) on it, you're not alone. It's one of the most common questions people ask before buying glasses online: "Why won't my optician give me my PD?" The short answer is that, in most places, they're simply not required to — and there are a few practical reasons it's often left off.

Is PD legally part of a glasses prescription?

In most regions, a written eyeglass prescription includes the powers for each eye (sphere, cylinder, axis) and sometimes add power for reading — but not your PD. In the United States and the United Kingdom, generally speaking, PD is treated as a fitting or dispensing measurement rather than part of the medical prescription itself. That means an optometrist or optician usually isn't obligated to write it down for you. (This is general information, not legal advice — rules vary by country and state, so it's worth checking your local guidance if it matters to you.)

Because PD isn't classed as part of the prescription, leaving it off isn't anyone breaking the rules. It's just where the line is typically drawn between "the prescription" and "the measurements taken when you buy glasses."

Common reasons your PD is withheld or charged for

Most opticians aren't trying to be difficult. There are a handful of everyday reasons your PD might not appear on the slip you walk out with:

• It's measured during dispensing. PD is normally taken in the store as part of fitting your frames, so it isn't generated until you actually choose glasses there. If you only had an eye exam, no one may have measured it yet.
• It's treated as a value-add for buying frames in-store. Some shops include the PD measurement as part of the service when you purchase glasses with them, and don't hand it out separately.
• Competitive reasons. An accurate PD makes ordering affordable glasses online very easy. It's understandable that a business whose revenue comes from selling frames may not be eager to remove the one remaining hurdle to shopping elsewhere.
• A small fee. A few practices will measure and provide your PD on request, sometimes for a modest charge, since it's a few minutes of a trained dispenser's time.

It's worth being fair here: opticians provide real value. A good dispenser checks frame fit, lens centration, and comfort in ways a quick home measurement doesn't. None of that is undermined by you also knowing your own PD.

How to measure PD without an optician

The good news is that PD is one of the easiest measurements to take yourself. Learning how to measure PD without an optician takes a few minutes, a mirror or a phone camera, and a steady hand — it isn't difficult or dangerous, and millions of people do it before buying glasses online.

You have two realistic options:

1. Politely ask. Call or visit and simply request your PD. Plenty of opticians will provide it, sometimes for free. A friendly "Could you include my PD, please?" goes a long way.
2. Measure it yourself. If you'd rather not ask — or you've already been turned down — measure PD without an optician at home. Our free PD measuring tool guides you through it using your camera or a photo, and even gives you a confidence range so you know how reliable your result is. Nothing is uploaded.

If you prefer a no-camera method, you can use a printable PD ruler and a mirror. Either way, self-measuring is completely legitimate — your PD is just the distance between your pupils, and you're allowed to know your own measurements.

For a full walkthrough, see how to measure your pupillary distance, and if you're new to the term, our explainer on what pupillary distance is covers the basics in plain language.

Frequently asked questions

Can my optician refuse to give me my PD?

Generally, yes — since PD usually isn't part of the formal prescription, an optician typically isn't required to provide it. Many will if you ask nicely, but if they decline, measuring it yourself is a perfectly reasonable alternative.

Is it safe and accurate to measure my own PD?

Yes. Measuring your own PD is safe and, with a good method, accurate enough for ordering most everyday glasses. Using a tool that reports a confidence range helps you double-check before you order, and you can always re-measure to confirm.

Do I really need my PD to buy glasses online?

For single-vision glasses, an accurate PD helps the optical center of each lens line up with your pupils, which keeps your vision comfortable. So while some retailers will accept a standard estimate, knowing your real PD gives you the best result.