Ring size by country
Different countries use completely different scales. Here's which system each uses — and a converter so the numbers actually line up.
Your size is US 7 (UK N½, EU 54).
Fit confidence Exact table match
Measurement confidence 70/100 · Medium Standard chart conversion; final fit still depends on band width and knuckle shape. Confirm with a printable or physical sizer before ordering an expensive ring.
- US
- 7
- UK
- N½
- EU / ISO
- 54
- Japan
- 14
- CH / IT / ES
- 14
- Ø mm
- 17.32
- Circ mm
- 54.4
| US | UK | EU | JP | CH | Ø mm | Circ mm |
|---|---|---|---|---|---|---|
| 3 | F½ | 44 | 4 | 4 | 14.07 | 44.2 |
| 3.5 | G½ | 45 | 5 | 5 | 14.48 | 45.5 |
| 4 | H½ | 47 | 7 | 7 | 14.88 | 46.8 |
| 4.5 | I½ | 48 | 8 | 8 | 15.29 | 48.0 |
| 5 | J½ | 49 | 9 | 9 | 15.70 | 49.3 |
| 5.5 | K½ | 51 | 10 | 11 | 16.10 | 50.6 |
| 6 | L½ | 52 | 12 | 12 | 16.51 | 51.9 |
| 6.5 | M½ | 53 | 13 | 13 | 16.92 | 53.1 |
| 7 | N½ | 54 | 14 | 14 | 17.32 | 54.4 |
| 7.5 | O½ | 56 | 15 | 16 | 17.73 | 55.7 |
| 8 | P½ | 57 | 16 | 17 | 18.14 | 57.0 |
| 8.5 | Q½ | 58 | 17 | 18 | 18.54 | 58.3 |
| 9 | R½ | 60 | 18 | 20 | 18.95 | 59.5 |
| 9.5 | S½ | 61 | 19 | 21 | 19.35 | 60.8 |
| 10 | T½ | 62 | 20 | 22 | 19.76 | 62.1 |
| 10.5 | U½ | 63 | 22 | 23 | 20.17 | 63.4 |
| 11 | V½ | 65 | 23 | 25 | 20.57 | 64.6 |
| 11.5 | W½ | 66 | 24 | 26 | 20.98 | 65.9 |
| 12 | Y | 67 | 25 | 27 | 21.39 | 67.2 |
| 12.5 | Z | 68 | 26 | 28 | 21.79 | 68.5 |
| 13 | Z½ | 70 | 27 | 30 | 22.20 | 69.7 |
Which system each country uses
| Country / region | System | Based on | Note |
|---|---|---|---|
| USA, Canada, Mexico | US numeric (½ steps) | Inner diameter | The number is set by inner diameter in inches. |
| UK, Ireland, Australia, NZ, South Africa | Letters A–Z (+½) | Circumference | Same alphabetic scale; US 7 = UK N½. |
| France, Germany, EU (ISO 8653) | EU / ISO number | Circumference (mm) | The size number IS the inner circumference in mm. |
| Japan | JP number | Lookup (JIS) | Own scale; no half sizes, skips some numbers. |
| Switzerland, Italy, Spain | Number | Circumference − 40 | Size ≈ circumference in mm minus 40. |
| India | Indian number | Lookup | Own numeric scale; treat conversions as approximate. |
| China | HK number or ISO mm | Mixed | Two conventions coexist; order by mm when possible. |
The cleanest, most universal measurement is millimetres: see the full chart with diameter and circumference for every size.
Frequently asked questions
Which ring size system does the US use?
The US (and Canada and Mexico) use a numeric system in half-size steps based on the ring’s inner diameter in inches.
What ring size system does Europe use?
Most of continental Europe uses the EU/ISO 8653 system, where the size number equals the inner circumference in millimetres (so EU 54 = 54 mm).
Why are UK ring sizes letters?
The UK, Ireland and Australia share an alphabetic scale (A–Z with half sizes) based on circumference. US whole sizes usually fall on a UK half letter — for example US 7 = UK N½.