How-to & tools
Ring size chart (US, EU and UK)
A full conversion table between US numbers, European circumference sizes, UK letters and inner diameter.
Written by our in-house jewelry team · Updated June 12, 2026 · 4 min read
In short
US ring sizes are numbers, UK sizes are letters and most European sizes are simply the inside circumference in millimeters. A US 6 is about 51.9 mm, a UK L1/2 and an EU 52. Use inside circumference as the common language between the three systems, and remember an antique ring's resizing range is limited by its setting.
One reference table for the three systems you will meet when buying jewelry across the Atlantic. US sizes are a number, European sizes are the inner circumference in millimeters, and UK sizes are a letter.
Every ring we sell is listed in both US and European sizes, so this chart is here for the ring already in your jewelry box. If you do not know your size yet, read how to measure your ring size first.
Shop the pieces: Solitaire, curated and available now.
| US | EU | UK | Diameter | Circumference |
|---|---|---|---|---|
| 3 | 44 | F | 14.1 mm / 0.56" | 44.0 mm |
| 3½ | 45.5 | G | 14.5 mm / 0.57" | 45.5 mm |
| 4 | 47 | H | 14.9 mm / 0.59" | 47.0 mm |
| 4½ | 48 | I | 15.3 mm / 0.60" | 48.0 mm |
| 5 | 49.5 | J½ | 15.7 mm / 0.62" | 49.5 mm |
| 5½ | 50.5 | L | 16.1 mm / 0.63" | 50.5 mm |
| 6 | 52 | M | 16.5 mm / 0.65" | 52.0 mm |
| 6½ | 53 | N | 16.9 mm / 0.67" | 53.0 mm |
| 7 | 54.5 | O | 17.3 mm / 0.68" | 54.5 mm |
| 7½ | 56 | P | 17.7 mm / 0.70" | 56.0 mm |
| 8 | 57 | Q | 18.1 mm / 0.71" | 57.0 mm |
| 8½ | 58.5 | Q½ | 18.5 mm / 0.73" | 58.5 mm |
| 9 | 59.5 | R½ | 18.9 mm / 0.74" | 59.5 mm |
| 9½ | 61 | S½ | 19.4 mm / 0.76" | 61.0 mm |
| 10 | 62 | T½ | 19.8 mm / 0.78" | 62.0 mm |
| 10½ | 63.5 | U½ | 20.2 mm / 0.80" | 63.5 mm |
| 11 | 64.5 | V½ | 20.6 mm / 0.81" | 64.5 mm |
| 11½ | 66 | W½ | 21.0 mm / 0.83" | 66.0 mm |
| 12 | 67 | Y | 21.4 mm / 0.84" | 67.0 mm |
| 12½ | 68.5 | Z | 21.8 mm / 0.86" | 68.5 mm |
| 13 | 70 | Z+1 | 22.2 mm / 0.87" | 70.0 mm |
Print at 100 percent with page scaling off, then check the calibration ruler before cutting.
How the three systems relate
European sizing is the most literal: the number is the inner circumference of the band in millimeters, so a size 54 ring measures 54 mm around the inside. US sizing is a scale where one full size is about 0.8 mm of circumference, or roughly 0.4 mm of diameter. UK sizing uses letters, with half sizes marked by a fraction.
Because the systems were never designed to match, some sizes fall between one another. Jewelers round to the nearest half size, and so do we, marking a conversion as approximate where it does not land exactly.
Using the chart
Find the row you know and read across. Diameter is the measurement across the inside of the band, which is what you get when you lay a ring on a ruler. Circumference is the measurement around the inside, which is what you get from a paper strip.
Frequently asked questions
- Is European ring size the same as the circumference in mm?
- Yes. The European (ISO 8653) size is the inner circumference of the band in millimeters, so a size 54 has a 54 mm inner circumference and a 17.2 mm inner diameter.
- What is a US size 7 in EU and UK sizes?
- A US 7 is approximately a European 54 to 54.5 and a UK O, with an inner diameter of about 17.3 mm.
- Why do conversion charts differ slightly between jewelers?
- The systems do not align exactly, so each house rounds a little differently. Differences are normally a quarter size, which is within the range that fit, band width and temperature affect anyway.
Written by our estate jewelry team and reviewed by our in-house gemologist. We have been buying and selling European antique jewelry since 1973.
From the reading to the piece
Shop vintage rings
Each piece is one of a kind and sells once, so this collection changes constantly.
View solitaireRelated guides
Keep reading
how-to
How to measure your ring size
Four ways to find your size at home, the traps that make people order a size wrong, and a converter between US, EU and UK sizes.
buying
The vintage engagement ring buying guide
Everything we would want a friend to know before spending several thousand dollars on a ring made a century ago.
authenticity
How to care for your vintage jewelry
Why repolishing can halve the value of a piece that took a century to earn its surface.