Estimate lens power and pupillary distance — a buying reference for your next pair.
On the Measure tab, tap “Print the test target” to print the 8 mm dot sheet (print at 100% / “Actual Size”). Lay it flat in even light, hold your glasses about 10 cm above it with one lens up, and shoot straight down so the dots show through and around the lens. Then tap the centre of your lens in the photo to read it.
The reading is a ratio, so any regular grid works: graph paper, or the app's on-screen grid shown on a second device (“Show the grid full-screen”). Photograph through the lens, switch the Auto/Manual toggle to Manual, and drag the points onto the dots yourself — that avoids the glare and moiré that trip up automatic detection on screens.
That means the grid was found and RxLens is waiting for you to tap the centre of the lens you're measuring in the photo — right where you can see dots through the glass. Tapping is the measurement.
Keep the phone flat (watch the level), set the height accurately, and take three readings so RxLens can average them. For best accuracy, calibrate once: measure a lens whose power you already know (e.g. a reader stamped “+1.50”) under the ⚙ button, and RxLens corrects every reading after that.
Best on single-vision sphere lenses — readers and simple near/farsighted glasses — plus pupillary distance. It does not read astigmatism (cylinder/axis), progressives, or bifocals, and it is not an eye exam.
Open “Measure PD”, hold the phone at arm's length with your face centred and eyes on the camera, and hold still until the reading steadies. PD is measured with the TrueDepth camera and needs a Face ID-capable iPhone.
RxLens has no account and makes no network calls — every measurement and photo stays on your device. See the Privacy Policy.
RxLens gives estimates for buying reference only. It is not a medical device — confirm anything important with an optician or an eye exam.
RxLens is an independent app and is not affiliated with any optical retailer or manufacturer.