UK to EU ring size converter
UK letters and EU numbers both trace back to the ring’s inner circumference, which makes conversion reliable. Each UK letter step is about 1.25 mm, and the EU number equals that circumference in mm. A UK L is around EU 51; a UK N is around EU 54. Convert below.
Quick answer
A UK N½ is 54 in EU (about 54.4 mm inner circumference). Use the converter for your exact size, or the chart below for the full range.
Between two sizes? Size up for a comfortable fit, see how to measure accurately.
UK → EU at a glance
- H½ = 47
- J½ = 49
- L½ = 52
- N½ = 54
- P½ = 57
- R½ = 59
- T½ = 62
- V½ = 65
UK to EU ring size chart
| UKUK / AU | EUEU / ISO | mmCircumference | mmDiameter |
|---|---|---|---|
| H½ | 47 | 46.7 | 14.9 |
| I½ | 48 | 48.0 | 15.3 |
| J½ | 49 | 49.3 | 15.7 |
| K½ | 51 | 50.5 | 16.1 |
| L½ | 52 | 51.8 | 16.5 |
| M½ | 53 | 53.1 | 16.9 |
| N½ | 54 | 54.4 | 17.3 |
| O½ | 56 | 55.6 | 17.7 |
| P½ | 57 | 56.9 | 18.1 |
| Q½ | 58 | 58.2 | 18.5 |
| R½ | 59 | 59.5 | 18.9 |
| S½ | 61 | 60.7 | 19.3 |
| T½ | 62 | 62.0 | 19.7 |
| U½ | 63 | 63.3 | 20.1 |
| V½ | 65 | 64.6 | 20.5 |
| W½ | 66 | 65.8 | 21.0 |
| X½ | 67 | 67.1 | 21.4 |
Both scales are millimetres in disguise
This is the most direct of all the conversions, because neither system is really abstract. A European size is the inner circumference in millimetres. A UK letter is the same circumference, counted in 1.25 mm steps up from 40 mm at size C.
So converting a letter to a European number is arithmetic with no judgement involved: work out the millimetres your letter represents, then round to the nearest whole one.
European numbers move faster than letters
One UK letter is 1.25 mm and one European size is 1 mm, so the European number climbs slightly faster than the alphabet. Every four letters gains you about five European sizes.
That mismatch is why half letters exist in the converted results. A UK L is close to EU 51 and a UK L½ is close to EU 52, so the halves fill gaps that whole letters would otherwise skip over.
Shopping across the Channel
British shoppers buying from European sites hit this conversion most often, usually with an Italian or French brand. Ask for the size in millimetres if the site offers it, because a millimetre figure removes every rounding step between you and the ring.
If the retailer is Italian, Spanish or Swiss, check whether their number is the circumference or the circumference minus 40. A size 14 from an Italian jeweller is an EU 54, not a tiny ring.
Common questions
How do I convert a UK ring size to EU?
Enter your UK size in the converter above and read the EU result, or find your row in the chart below. Every value is calculated from the ring’s inner circumference, so it works in both directions.
What is a UK N½ in EU?
A UK N½ is 54 in EU. That ring has an inner circumference of about 54.4 mm.
Related conversions
Or see the full ring size chart.