Mila's Ring Size Converter PRO
Eight international ring systems — convert or measure on your iPhone screen.
About Mila's Ring Size Converter PRO
Shopping for a ring online usually means decoding a chart: US half sizes, EU whole numbers, Japanese and Chinese scales, Swiss sizing, Hong Kong standards — plus diameter and circumference in millimeters. Mila's Ring Size Converter PRO is a focused iPhone app from the developer of Mila's Tools (Apple Staff Pick, 4.8 from 1,200+ reviews) that puts every major system on one screen and updates them as you type.
Eight sizing systems, one field
Enter any value you know — a US 7, an EU 54, an inner diameter in mm — and the app shows the equivalent across inner diameter, inner circumference, US, EU (Continental), Swiss, Japanese, Chinese (Mainland), and Hong Kong sizes. Results use each region's real increments (half sizes for US, whole numbers where those markets expect them), so you see a jeweler-ready size, not a long decimal.
Measure on your iPhone when you do not know your size
- Match a ring on screen — place a ring you already own on the display and tap the circle that fits; US sizes 3 through 15 in half steps
- Measure with string — wrap paper or string around your finger, then read length on a calibrated on-screen ruler (0.5 mm precision)
- Coin calibration — one-time screen calibration with a common coin; 13 reference coins for major currencies, with a regional default
Good for
- Engagement and wedding band shopping from international retailers
- Surprise gifts when you can borrow a ring for a few minutes
- Comparing EU, UK-adjacent, and Asian listings on the same order page
- Travel or duty-free jewelry where the tag uses an unfamiliar scale
Frequently asked questions
- How is this different from the ring tool in Mila's Tools?
- Same conversion engine and measurement features, packaged as a standalone app with a ring-first layout — no scrolling through 28 other converter categories.
- Do I need internet to convert or measure?
- No. Conversions and on-screen measurement work fully offline; sizing data stays on your device.
- Which ring size systems are supported?
- US, EU (Continental), Swiss, Japanese, Chinese (Mainland), Hong Kong, plus inner diameter and circumference in millimeters.
- How accurate is on-screen measurement?
- Accuracy depends on a one-time coin calibration against your display. The app includes reference coins for many regions and reads string or ring matching to 0.5 mm on the ruler.
Privacy
Mila's Ring Size Converter does not send your measurements or conversions to a server. Calibration and sizing work on your iPhone.