The Size Guide
Find your perfect size.
Use a ring you already love to measure your size — accurately, in under a minute. Our interactive tool converts the inner diameter to US, European and UK sizing.
Step 1 — Calibration
Calibrate your screen with a bank card.
Hold a credit or bank card (85.60 × 53.98 mm) against the screen and move the slider until the rectangle matches the card exactly.
1. Choose a ring
Pick a ring that fits the finger you intend to wear your CASALYA on. Make sure it slides on comfortably and doesn't twist.
2. Measure the inner diameter
Place the ring on a flat surface and measure across the inside (edge to edge) in millimetres with a ruler.
3. Match it below
Adjust the slider to your measured diameter — your CASALYA size will appear instantly.
Alternative Method
No ruler? No problem.
If you don't have a ruler at hand, the string method works almost as well:
- Wrap a thin strip of paper or a piece of string around the base of your finger.
- Mark where it overlaps — gently, without pulling tight.
- Measure the length in millimetres — that's your finger's circumference.
- Divide by 3.14 to get the inner diameter, then use the slider above.
Reference
International size chart
A complete conversion between inner diameter, US, European and UK ring sizes.
| Diameter (mm) | US | EU | UK |
|---|---|---|---|
| 14.0 | 3 | 44 | F |
| 14.4 | 3.5 | 45 | G |
| 14.8 | 4 | 46.5 | H |
| 15.2 | 4.5 | 47.5 | I |
| 15.6 | 5 | 49 | J½ |
| 16.0 | 5.5 | 50 | K½ |
| 16.5 | 6 | 51.5 | L½ |
| 16.9 | 6.5 | 52.5 | M½ |
| 17.3 | 7 | 54 | N½ |
| 17.7 | 7.5 | 55 | O½ |
| 18.1 | 8 | 56.5 | P½ |
| 18.5 | 8.5 | 58 | Q½ |
| 19.0 | 9 | 59 | R½ |
| 19.4 | 9.5 | 60.5 | S½ |
| 19.8 | 10 | 61.5 | T½ |
| 20.2 | 10.5 | 63 | U½ |
| 20.6 | 11 | 64 | V½ |
A few last words
For a perfect fit.
Measure in the evening
Fingers swell slightly throughout the day. An evening measurement gives the most reliable everyday fit.
Mind the temperature
Cold fingers measure smaller. Take your reading at a normal, comfortable room temperature.
When in doubt, size up
If you're between two sizes, choose the larger one — especially for wider band designs.