How to Use This Guide
- Measure the inside diameter of a ring you already own (in millimeters).
- Find that diameter in the first column of the chart.
- Match it with your country’s sizing system (US, UK, EU, JP, etc.).
Ring Size Conversion Chart (Sample)
Below is a sample of the conversion table used in the app. The full chart in the app covers every quarter size for even more accuracy.
| Diameter (mm) | United States / Canada / Mexico | United Kingdom / Ireland / Australia / NZ / SA | China | Japan | South Korea | India | Italy | Spain | Netherlands | Switzerland | Europe (EU) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 11.63 | 0 | – | – | – | – | – | -3.5 | -3.5 | -3.5 | -3.5 | 36.5 |
| 12.04 | 1/2 | A | – | – | – | – | -2.2 | -2.2 | -2.2 | -2.2 | 37.8 |
| 12.45 | 1 | B | 1 | 1 | 1 | – | -0.9 | -0.9 | -0.9 | -0.9 | 39.1 |
| 13.26 | 2 | D | 2 | 2 | 2 | 2 | 1.7 | 1.7 | 1.7 | 1.7 | 41.7 |
| 14.07 | 3 | F | 4 | 4 | 4 | – | 4.2 | 4.2 | 4.2 | 4.2 | 44 |
| 15.29 | 4 1/2 | I | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 48 |
| 16.51 | 6 | L 1/2 | 11 | 11 | 11 | 12 | 11.9 | 11.9 | 11.9 | 11.9 | 51.9 |
| 17.32 | 7 | N 1/2 | 14 | 14 | 14 | 14 | 14.4 | 14.4 | 14.4 | 14.4 | 54 |
| 18.14 | 8 | P 1/2 | 16 | 16 | 16 | 17 | 17 | 17 | 17 | 17 | 57 |
| 19.35 | 9 1/2 | S 1/2 | 19 | 19 | 19 | 21 | 20.8 | 20.8 | 20.8 | 20.8 | 61 |
| 20.57 | 11 | V 1/2 | 23 | 23 | 23 | 25 | 24.6 | 24.6 | 24.6 | 24.6 | 64.6 |
| 22.00 | 12 3/4 | Z | 29 | 29 | 29 | 29 | 29.1 | 29.1 | 29.1 | 29.1 | 69 |
| 23.22 | 14 1/4 | Z3 | – | – | – | 33 | 32.9 | 32.9 | 32.9 | 32.9 | 73 |
| 24.64 | 16 | – | – | – | – | 37 | 37.4 | 37.4 | 37.4 | 37.4 | 77.4 |
👉 The full chart inside the app covers every quarter size for even more accuracy.
Tips for Measuring Ring Size
- Measure in the evening: Fingers are slightly larger at night.
- Avoid the cold: Low temperatures shrink your fingers.
- Measure multiple times: Repeat measurements to reduce error.
- Remember dominant-hand differences: Your writing hand can be half a size larger.
Why Use the Ring Sizer App?
- Place your ring on the screen to find the exact size.
- Instantly switch between US, UK, EU, JP, and other systems.
- Save your size profile for future purchases.
Final Thoughts
A ring should feel comfortable, secure, and easy to wear every day. With this guide and our app, you can confidently order the perfect fit—no matter where in the world your jeweler is.