US to EU Ring Size Converter
European ring sizes look confusing until you know the trick: the number is simply the inside circumference of the ring in millimetres.
Quick answer
US 7 is EU 54, meaning the ring measures about 54 mm around the inside. Add roughly 2.5 mm of EU size for every full US size.
Instant Converter
Change any field — the rest update automatically.
Inside circumference, mm
Inside
Inside
Inside
Inside
Matched inside diameter 17.30 mm · circumference 54.35 mm
Conversion table
| US | EU (ISO) | Inside diameter | Circumference |
|---|---|---|---|
| 3 | 44 | 14.00 mm | 44.0 mm |
| 3.5 | 45 | 14.40 mm | 45.2 mm |
| 4 | 47 | 14.80 mm | 46.5 mm |
| 4.5 | 48 | 15.20 mm | 47.8 mm |
| 5 | 49 | 15.60 mm | 49.0 mm |
| 5.5 | 50 | 16.00 mm | 50.3 mm |
| 6 | 52 | 16.45 mm | 51.7 mm |
| 6.5 | 53 | 16.90 mm | 53.1 mm |
| 7 | 54 | 17.30 mm | 54.3 mm |
| 7.5 | 56 | 17.70 mm | 55.6 mm |
| 8 | 57 | 18.10 mm | 56.9 mm |
| 8.5 | 58 | 18.50 mm | 58.1 mm |
| 9 | 59 | 19.00 mm | 59.7 mm |
| 9.5 | 61 | 19.40 mm | 60.9 mm |
| 10 | 62 | 19.80 mm | 62.2 mm |
| 10.5 | 63 | 20.20 mm | 63.5 mm |
| 11 | 65 | 20.60 mm | 64.7 mm |
| 11.5 | 66 | 21.00 mm | 66.0 mm |
| 12 | 67 | 21.40 mm | 67.2 mm |
| 12.5 | 68 | 21.80 mm | 68.5 mm |
| 13 | 70 | 22.20 mm | 69.7 mm |
How the European scale works
The ISO 8653 standard defines a ring size as its inside circumference in millimetres. An EU 54 ring is 54 mm around the inside, which works out at 17.2 mm across.
France, Germany, Italy, Spain and Scandinavia all use this system, although some older German and Swiss charts subtract 40 from the number.
Popular US to EU conversions
- US 5 = EU 49
- US 6 = EU 52
- US 7 = EU 54
- US 8 = EU 57
- US 9 = EU 59
- US 10 = EU 62
Ordering from a European jeweller
If you know your finger circumference in millimetres you already know your European size — just round to the nearest whole number. That makes EU sizing the most reliable way to order a ring online from abroad.
Frequently asked questions
Is EU ring size the same as circumference in mm?
Yes. Under ISO 8653 the European ring size is the inside circumference in millimetres, rounded to the nearest whole number.
What is EU 54 in US sizes?
EU 54 is a US 7, an inside diameter of about 17.2 mm.
Keep reading
For an expensive ring, confirm the size with a jeweller before ordering — see the ring size FAQs for resizing advice.