The basics, explained

Your pupillary distance is the distance in millimeters between the centers of your two pupils. Online opticians ask for it so your lenses line up with your eyes, and it's typically between 54 mm and 74 mm for adults.

Yes. Pupillary Distance is an iPhone app that measures your PD with the front-facing TrueDepth camera — the same depth camera that powers Face ID.

The app uses TrueDepth AR face tracking to locate the center of each pupil in 3D and measure the distance between them. It reports your far PD, your near PD, and your left and right monocular PD in millimeters.

It's free to download and try. A subscription unlocks PD measurement and frame recommendations — there are no ads, and no signup to get started.

No. Measurements run entirely on your device — there is no server and nothing is uploaded, so it works without a connection.

Any iPhone with a TrueDepth front camera (iPhone X and later) running iOS 16 or newer. The app is iPhone-only.

Far PD is measured as if you are looking into the distance and is used for most glasses. Near PD is slightly smaller because your eyes converge when reading. The app reports both.

Monocular PD is the distance from the center of your nose bridge to each pupil, measured separately for the left and right eye. It matters when your eyes are not perfectly symmetrical, and the app reports both values.

It gives an accurate millimeter PD that works well for everyday eyewear. For progressives, high prescriptions, or specialized lenses, use the app as a starting point and confirm with an optician.

They measure the same thing in millimeters. In a 2024 peer-reviewed comparison, a smartphone front-camera PD app differed from a clinical pupillometer by an average of 0.6 mm — inside the tolerance spectacles are manufactured to. That study tested a different app, not ours, so treat it as an indication of what depth-based measurement can do rather than a guarantee. For critical prescriptions, double-check with an eye-care professional.

Yes. A short guided survey about your face shape, nose bridge, and face width produces eyeglass frame style suggestions to help you choose flattering frames.

Yes. Remove your glasses so the camera can see your pupils clearly. Tinted or reflective lenses can hide the pupil and throw off the reading.

Open the app, hold the iPhone at about arm’s length and level with your eyes, and look straight into the front camera. Keep your head still in even lighting and tap Measure. Running it twice helps confirm a consistent result.

Common reasons: the lighting is too dim or uneven, the phone is too close or too far, or something is covering your eyes. Move to brighter, even light, hold the phone at arm’s length, and make sure your full face is in frame.

No calibration is required. Just open the app, allow camera access, and measure. TrueDepth handles the depth sensing for you.

Yes. You can save your PD results on the device and review them later, and share a result when an online optician asks for your PD.

The camera is used live only while you are measuring. No photo or video is recorded, and nothing from the camera is saved or transmitted.

No. Pupillary Distance is iPhone-only because it relies on the iPhone’s TrueDepth front camera. There is no Android version.

Yes. Measurements are stored only on your device, there is no account, and nothing is uploaded to a server. Your camera is used live for measuring and never saved or shared.

Subscriptions are billed through your Apple ID and can be weekly or yearly. Manage or cancel anytime in Settings > your name > Subscriptions on your iPhone.