Ring size is the inner circumference in millimetres. The honest way to get it is to measure, not to guess — a quarter size off is the difference between a ring that spins and one you never take off.
Method 1: measure a ring you already wear
- Pick a ring that fits the exact finger you are buying for.
- Lay it flat and measure the inside diameter across the widest point.
- Multiply by 3.14 (π). That number is your EU size; compare it to the table below.
Method 2: measure the finger
- Cut a thin strip of paper, wrap it around the base of the finger.
- Mark where the paper meets, then measure the length in millimetres.
- Measure at the end of the day when fingers are largest — never first thing in the morning or straight out of the cold.
Size conversion
| Inside diameter | EU size | US size | UK size |
|---|---|---|---|
| 15.7 mm | 49 | 5 | J½ |
| 16.5 mm | 52 | 6 | L½ |
| 16.9 mm | 54 | 7 | N½ |
| 17.7 mm | 56 | 7¾ | P½ |
| 18.5 mm | 58 | 8½ | Q½–R |
| 19.4 mm | 61 | 9½ | T½ |
Details that change the size
- Wide bands (5 mm and up) need a half size larger than narrow ones.
- Knuckle-heavy hands: measure the knuckle too and size between the two readings.
- Stacking rings sit closer together when they are the same width — keep a set within one size of each other.