Ring Sizer vs DIAMETRO

Find your ring size in seconds — no trip to the jeweler needed. MEASURE WITH YOUR FINGER Place your finger on the screen and adjust the guide to estimate your size. Great when you don't have a ring to compare. MEASURE WITH A RING Place a ring you already own on the screen and match the circle to the inside edge. The most accurate way to find your size at home. EVERY SIZE SYSTEM YOU NEED See your result in US/CA, UK, JP, diameter (mm & inch), and circumference (mm) — all at once, no switching. SCREEN-CALIBRATED ACCURACY Auto-detects your iPhone model for precise on-screen measurements. SAVE & COMPARE Label and save measurements for yourself, a partner, or family. Come back anytime to check. Free. No ads. No account required.

Find your ring size in seconds, right on your iPhone. Place a ring you already own on the calibrated circle, slide until the bubble fills the inside of the ring, and DIAMETRO shows its size in EU/ISO, US, UK, CH and JP, plus the exact diameter and circumference. HOW IT WORKS • Calibrate once with a bank card or a coin for true physical scale • Lay your ring on the screen • Slide until it fits, then save the result DIAMETRO PRO • Finger measurement: enter the circumference of your finger and get a recommended size, with optional knuckle compensation • All accent colors • Unlimited saved measurements • Printable PDF sizer, export and backup (PDF, CSV, JSON) ALSO INSIDE • Light and Dark mode • English, Romanian and French PRIVATE BY DESIGN No account. No tracking. Your measurements stay on your device. Conversions are approximate. Confirm your size with a jeweler before buying.