DIAMETRO: Ring Sizer

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.