The pupillary distance app for iPhone
Pupillary Distance is an iOS app that measures your pupillary distance (PD) — the millimeter distance between your pupils that you need to order glasses online — using the iPhone's front camera and TrueDepth AR face tracking. It outputs far PD, near PD, and left/right monocular PD, and recommends eyeglass frames based on your face shape. This page is a ranked, opinionated shortlist of ways to get your PD — the app, an optician, and the free alternatives — with the honest tradeoffs. We build the top pick, so weigh it accordingly; the rest of the list is here to help you decide.
4.5 ★ · 135 ratings on the App Store
Comparison table
| # | Option | Price | Platform | Method | Best for |
|---|---|---|---|---|---|
| 1 | Pupillary Distance | Free trial | iPhone (iOS 16+) | TrueDepth AR face tracking | Ordering glasses online accurately |
| 2 | Ask your optician | Free with an exam | In person | Manual ruler / pupillometer | Strong prescriptions and a second opinion |
| 3 | Printable PD ruler | Free | Paper + mirror | Manual mirror measurement | A rough single-PD reading with no app |
| 4 | Webcam / desktop PD tool | Free | Laptop webcam | 2D photo + reference card | People without a recent iPhone |
| 5 | Generic App Store "PD" apps | Free / subscription | iOS | Varies (some 2D photo only) | Skip — see notes |
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#1 Pupillary Distance
Best overall · Free to try · iPhoneA PD measurement app for iPhone that uses the front camera and TrueDepth AR face tracking to read the millimeter distance between your pupils. It gives you far PD, near PD, and left/right monocular PD, plus frame-style suggestions based on your face shape. Free to try, ad-free, and fully on-device.
Pros- Real depth-based measurement, not a photo guess
- Outputs far, near, and monocular PD
- Private — measurements stay on your iPhone, no account
- Ad-free; also recommends frames for your face shape
Cons- Subscription after the free trial
- iPhone-only — needs a TrueDepth front camera
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#2 Ask your optician
Most authoritativeThe optician who did your eye exam can measure your PD in seconds with a pupillometer. It's the gold standard — but many will only print it on the prescription if you ask, and it means a trip in person.
Pros- Most authoritative reading
- Free if you ask during an exam
- Can include near PD for reading glasses
Cons- Requires an appointment or a return trip
- Some shops are reluctant to hand the number over
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#3 Printable PD ruler
Free, low-techPrint a millimeter ruler, hold it to your brow in a mirror, and line it up with your pupils. It costs nothing, but you're squinting at a reflection and reading your own eyes — small errors are easy and it only gives a single far PD.
Pros- Completely free
- No phone or app needed
Cons- Easy to misread in a mirror
- Usually only a single far PD
- Hard to get monocular PD on your own
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#4 Webcam / desktop PD tool
Reference-card dependentBrowser tools that use a laptop webcam usually ask you to hold a standard card (a credit card or coin) against your face for scale, then estimate PD from a flat photo. Workable in a pinch, but a 2D webcam has no real depth data, so accuracy hinges on holding the card perfectly flat.
Pros- Works on a laptop without an app
- Free to use
Cons- No true depth — scale comes from a card
- Sensitive to card angle and head tilt
- Often far PD only
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#5 Generic App Store "PD" apps
Check carefullyThe App Store has several pupil-distance apps. Some genuinely use TrueDepth; others estimate PD from a flat selfie or ask for a reference card, and a few lean on ads or aggressive paywalls. Read the reviews and the privacy details before trusting one with your prescription.
Cons- Some estimate from a 2D photo, not depth
- Ad-heavy or paywalled for basics
- Privacy practices vary widely
How we picked
Three things separate a pupil distance app worth trusting from one that just looks the part. First, it should measure real depth. The honest apps use the iPhone's TrueDepth front camera and AR face tracking, which gives a true three-dimensional read on where your pupils sit; weaker tools estimate PD from a flat selfie or ask you to hold a credit card against your face for scale, and a 2D photo simply has no depth data to work with. Second, it should give you the full set of numbers — far PD for distance glasses, near PD for reading, and left/right monocular PD — because a single average can hide the difference between your two eyes. Third, it should be private and ad-free: a measurement of your own face is personal, so it should stay on your device with no account and nothing uploaded.
For the top pick, that's exactly the bar Pupillary Distance is built to clear — depth-based measurement, far/near/monocular output, on-device storage, no ads. The rest of the list earns its place by being genuinely useful in the cases the app can't cover: an optician is the most authoritative reading and the right call for strong prescriptions, and a printable ruler or a webcam tool is a reasonable free fallback if you don't have a recent iPhone. If you want to try the measurement first, you can measure your PD online with your phone camera, and our guide on how to measure pupillary distance walks through every method by hand. To see exactly how the TrueDepth measurement works, read how it works.
One honest caveat: no measurement is infallible, including ours. On a modern TrueDepth iPhone the app lands within roughly a millimeter, but for high-power prescriptions we recommend taking two or three readings and averaging them — and if a number ever looks off against what your optician told you, trust the optician.
Common questions
Your PD, measured
in under a minute.
Pupillary Distance turns your iPhone into an accurate PD meter. Measure once, then order glasses online with confidence.
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