Ringbox - Ring Sizer

Find your ring size on your screen — no guessing, no printing, no trip to a jeweler.

Ringbox turns your iPhone into a true-to-scale ring sizer. Lay a ring you already own flat on the display, match the circle to it, and read your size in every system used worldwide. It takes about ten seconds.

THREE WAYS TO MEASURE • Ring on screen — the most accurate. Size the circle to the ring's inner edge. A magnifier follows your finger so you can see the exact moment the edges meet, and a haptic tick marks every quarter size. • Paper strip — no ring to hand? Wrap a strip of paper around your finger, mark where it overlaps, and lay it on the true-scale ruler. • Finger on screen — a quick estimate when you just want a ballpark. We label it honestly as ±1 size and tell you to confirm with a ring or a strip before you buy.

EVERY SIZING SYSTEM US & Canada, UK & Australia, Europe/ISO, Japan & China — plus inner diameter and circumference, in millimeters and inches. Type a size in any system and the converter shows all the others. The full ring size chart runs US 3 to 16 in half sizes.

ACCURATE, AND HONEST ABOUT IT Ringbox knows your exact screen size, so the circle is drawn at real physical scale rather than scaled to a guess. If your model isn't recognized, calibrate in seconds against any bank card. Double-check compares two measurements taken different ways and gives you a confidence badge, with a guided fix when they disagree. Between sizes? It tells you to round up, and why.

The fit tips are built in, too: wide bands need a little more room, fingers swell through the day, and the ring has to clear the knuckle.

A DRAWER FOR YOUR RINGS • Save any ring with a name, the person, the hand and the finger • Add a photo and the background is removed on device — a clean cut-out of the ring itself • Group rings by person: you, your partner, your mom, whoever

SURPRISE-PROOF Sizing a ring for a proposal? Secret profiles are hidden behind Face ID, so their rings, photos and sizes stay out of sight. A reminder about a secret person never shows a name or a size on your Lock Screen, and secret people are left out of widgets — a Home Screen isn't private.

WIDGETS, REMINDERS, PAPER • Home Screen widgets: one ring, a grid of your collection, or your size across every system • Gift reminders for birthdays and anniversaries, with the size right there in the notification • A printable paper ring sizer (PDF, Letter or A4) with a print-scale check, so you know it came out at 100% • Share cards showing a size in every system, with the ring's photo

PRIVATE BY DEFAULT It all happens on your iPhone. Photos are cut out on device, sizes are stored on device, and nothing needs an account or an internet connection.

Available in English, Spanish, French, German, Italian, Portuguese, Chinese and Hebrew.

FREE, AND THE DIAMOND PLAN Every way to measure is free — all three methods, every sizing system, the chart, the converter, calibration, and one saved ring with a photo. Measuring itself is never paywalled.

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