Ring Size Converter
Convert ring sizes between US, UK, EU and Australia using inner diameter and circumference, not a static chart image.
Find your equivalent size
Enter a size from your chart, or a measurement in the selected unit.
Choose the system and enter your size to see its equivalents.
Measure a ring that already fits well, or match your finger circumference. EU sizes are the inner circumference in millimeters. Size can shift with temperature and time of day; a jeweler's mandrel is the most reliable final check.
View the full ring size chart
| US / Canada | UK / Australia | EU | Inner diameter (mm) | Inner circumference (mm) |
|---|---|---|---|---|
| 3 | F | 44 | 14.1 mm | 44.2 mm |
| 3.5 | F½ | 45 | 14.5 mm | 45.5 mm |
| 4 | G½ | 47 | 14.9 mm | 46.8 mm |
| 4.5 | H½ | 48 | 15.3 mm | 48.0 mm |
| 5 | J½ | 49 | 15.7 mm | 49.3 mm |
| 5.5 | K½ | 51 | 16.1 mm | 50.6 mm |
| 6 | L½ | 52 | 16.5 mm | 51.9 mm |
| 6.5 | M½ | 53 | 16.9 mm | 53.2 mm |
| 7 | N½ | 54 | 17.3 mm | 54.4 mm |
| 7.5 | O½ | 56 | 17.7 mm | 55.7 mm |
| 8 | P½ | 57 | 18.1 mm | 57.0 mm |
| 8.5 | Q½ | 58 | 18.5 mm | 58.3 mm |
| 9 | R½ | 60 | 19.0 mm | 59.5 mm |
| 9.5 | S½ | 61 | 19.4 mm | 60.8 mm |
| 10 | T½ | 62 | 19.8 mm | 62.1 mm |
| 10.5 | U½ | 63 | 20.2 mm | 63.4 mm |
| 11 | V½ | 65 | 20.6 mm | 64.6 mm |
| 11.5 | W½ | 66 | 21.0 mm | 65.9 mm |
| 12 | X½ | 67 | 21.4 mm | 67.2 mm |
| 12.5 | Y½ | 68 | 21.8 mm | 68.5 mm |
| 13 | Z½ | 70 | 22.2 mm | 69.8 mm |
How ring sizes relate to each other
Every ring sizing system is really describing the same thing: the ring's inner diameter, or the circumference around the inside of the band. US and Canada use a numbered scale, the UK and Australia use letters, and most of Europe simply uses the inner circumference in millimeters as the size itself.
Example: a US size 7
- Inner diameter
- 17.3 mm
- Circumference
- 17.3 × π = 54.4 mm
A US 7 is roughly a UK N½ and an EU 54.
Getting an accurate measurement
- 01
Measure a ring that already fits
Measure the inside diameter of a ring worn on the same finger with a ruler, or wrap a strip of paper around the inside and measure its length for the circumference.
- 02
Match it in the table
Find the closest diameter or circumference in the table above and read across for the size in whichever system you're shopping in.
- 03
Confirm with a mandrel if it matters
For an engagement ring or anything expensive, have a jeweler measure the finger directly with a ring sizer. Finger size shifts slightly with temperature and time of day, so a paper strip at home is a starting point, not a guarantee.
Questions people ask
How accurate is a paper strip measurement?
It's a reasonable starting point but not exact, since paper stretches and it's easy to wrap it slightly loose or tight. For an important purchase, get measured with a metal ring sizer at a jeweler instead.
Why do ring size charts from different jewelers vary slightly?
There's no single enforced global standard, and mandrels from different manufacturers can differ by a fraction of a millimeter. Small differences between charts are normal; they generally agree within about half a size.
Does ring width affect sizing?
Yes. A wider band feels tighter than a narrow one at the same measured size, so many jewelers recommend going up half a size for a band wider than about 6mm.
What is EU ring sizing based on?
The inner circumference of the ring in millimeters, used directly as the size number, which is why an EU 54 ring has a 54mm inside circumference.
Related tools
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Emmanuel Asika
Shopify & WooCommerce developer, Dublin
I build and fix online stores: new builds, migrations, speed, SEO and the custom bits apps can't do.
Last reviewed 30 September 2026.