Find any ring size in under two minutes

SizeMyRing turns your iPhone into a precise ring-sizing instrument. Measure with a ring, finger, photo or string — then get every international size at once. No jeweler, no guesswork.

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Every ring standard, instantly

See US, UK, EU (ISO), Japan/China and Swiss sizes side by side — plus exact inner diameter and circumference in millimetres.

Lay a ring on the screen

Match the glowing circle to a ring's inner edge. Calibrate with any bank card for jeweler-grade accuracy.

Gift Mode

Measure a partner's ring discreetly in about 60 seconds — perfect for engagement rings.

The full size chart, always at hand

A complete conversion chart and a built-in converter for every region. Save sizes for the whole family and share a jeweler-ready card in a tap.

Why SizeMyRing

Four ways to measure

A ring, your finger, a photo, or a piece of string — whatever you have on hand.

Private by design

Everything is measured and stored on your iPhone. No account, and photos never leave your device.

Jeweler-grade accuracy

Calibrate your screen with any standard payment card so on-screen measurements are precise.