EU / ISO
Ring sizes in Europe.
Most of Europe uses ISO 8653, where the size simply is the inside circumference in millimetres. A size 52 ring measures 52 mm around the inside. It is the most transparent system in use anywhere, which is why we recommend quoting it internationally.
- The number means
- Size = inside circumference in millimetres
- Written as
- a two-digit number — “fifty-two”
Worth knowing: ISO 8653:2016 tabulates 41–76 mm with a ±0.02 mm tolerance.
EU / ISO sizes converted
Every row is calculated from the published standards, so the columns stay consistent with one another.
Scroll the table sideways to see every region
| EU / ISO | Diameter | Circum. | US / CA | UK / AU | France | DE / NL | Russia |
|---|---|---|---|---|---|---|---|
| 47 | 14.88 mm | 46.8 mm | 4 | H½ | 47 | 15 | 15 |
| 48 | 15.29 mm | 48.0 mm | 4½ | I½ | 48 | 15.5 | 15.5 |
| 49.5 | 15.69 mm | 49.3 mm | 5 | J½ | 49.5 | 15.5 | 15.5 |
| 50.5 | 16.10 mm | 50.6 mm | 5½ | K½ | 50.5 | 16 | 16 |
| 52 | 16.51 mm | 51.9 mm | 6 | L½ | 52 | 16.5 | 16.5 |
| 53 | 16.91 mm | 53.1 mm | 6½ | M½ | 53 | 17 | 17 |
| 54.5 | 17.32 mm | 54.4 mm | 7 | N½ | 54.5 | 17.5 | 17.5 |
| 55.5 | 17.73 mm | 55.7 mm | 7½ | O½ | 55.5 | 17.5 | 17.5 |
| 57 | 18.13 mm | 57.0 mm | 8 | P½ | 57 | 18 | 18 |
| 58 | 18.54 mm | 58.2 mm | 8½ | Q½ | 58 | 18.5 | 18.5 |
| 59.5 | 18.95 mm | 59.5 mm | 9 | R½ | 59.5 | 19 | 19 |
| 61 | 19.35 mm | 60.8 mm | 9½ | S½ | 61 | 19.5 | 19.5 |
| 62 | 19.76 mm | 62.1 mm | 10 | T½ | 62 | 20 | 20 |
| 63.5 | 20.16 mm | 63.3 mm | 10½ | U½ | 63.5 | 20 | 20 |
| 64.5 | 20.57 mm | 64.6 mm | 11 | V½ | 64.5 | 20.5 | 20.5 |
| 66 | 20.98 mm | 65.9 mm | 11½ | W½ | 66 | 21 | 21 |
| 67 | 21.38 mm | 67.2 mm | 12 | X½ | 67 | 21.5 | 21.5 |
| 68.5 | 21.79 mm | 68.5 mm | 12½ | Z | 68.5 | 22 | 22 |
| 69.5 | 22.20 mm | 69.7 mm | 13 | Z+1 | 69.5 | 22 | 22 |
Need a standard that isn’t shown? The full conversion chart lists all11 side by side.
Calibration
Calibrate with something in your pocket.
You don’t need a bank card. Our sizer knows the published diameter of coins from your currency, so you can calibrate with whatever is nearest.
€1
23.25 mm across
European Central Bank coin specifications
€2
25.75 mm across
European Central Bank coin specifications
50 cent
24.25 mm across
European Central Bank coin specifications
Buying from abroad
If you’re ordering from a retailer that uses a different scale, don’t translate the size yourself and hope. Send them the inside diameter in millimetres — every workshop in the world can work from that, and it removes the rounding step where errors creep in.
The reason is that the scales have different step sizes. A whole size in one system rarely lands exactly on a whole size elsewhere, so somebody has to round. Better that it’s the jeweller holding your measurement than a chart guessing at it.