How to Convert Ring Sizes Between US, EU, UK, and International Systems
To convert ring sizes between US, EU, UK, and international systems, use the conversion table below, which maps every US size to its equivalent in European, British, Australian, and Japanese sizing based on the ring's inner diameter and circumference in millimeters. Ring sizing systems vary by country, and a size 6 in the United States does not translate directly to a 6 in Europe, the UK, or Asia. If you are ordering from an international jeweler, converting a ring someone gifted you from abroad, or simply trying to make sense of a size chart that uses unfamiliar numbers, this conversion table eliminates the confusion. Antoanetta uses US sizing as the standard.
How Are Ring Sizes Measured in Different Countries?
All ring sizing systems are based on the same two physical measurements: the inner diameter of the ring (measured in millimeters) and the inner circumference (also in millimeters). The difference between systems is simply how they label those measurements.
US and Canada: Use a numerical scale with whole and half sizes. Size 1 is the smallest, and sizes increase in increments of approximately 0.8mm in diameter. The most common women's range is 4 to 8.
UK, Australia, and South Africa: Use an alphabetical scale. Size A is the smallest, progressing through the alphabet. The most common women's range is H to Q.
Europe (including France, Germany, Italy, Spain, and Scandinavia): Use the inner circumference in millimeters as the size number. A European size 52 means the ring has an inner circumference of 52mm.
Japan: Uses a numbered scale that does not match US numbers. A Japanese size 1 corresponds roughly to US size 1, but the increments differ, so the systems diverge as sizes increase.
US, EU, UK, and International Ring Size Conversion Table
| US / Canada | UK / Australia | Europe | Japan | Inside Diameter (mm) | Inside Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.0 | 44.0 |
| 3.5 | G | 45.5 | 5 | 14.4 | 45.5 |
| 4 | H | 47 | 7 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 48.0 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50.5 | 10 | 16.1 | 50.6 |
| 6 | L | 51.5 | 12 | 16.5 | 51.8 |
| 6.5 | M | 53 | 13 | 16.9 | 53.1 |
| 7 | N | 54 | 14 | 17.3 | 54.4 |
| 7.5 | O | 55.5 | 15 | 17.7 | 55.7 |
| 8 | P | 57 | 16 | 18.2 | 57.0 |
| 8.5 | Q | 58 | 17 | 18.6 | 58.3 |
| 9 | R | 59 | 18 | 19.0 | 59.5 |
| 9.5 | S | 61 | 19 | 19.4 | 60.8 |
| 10 | T | 62 | 21 | 19.8 | 62.1 |
| 10.5 | U | 63.5 | 22 | 20.2 | 63.4 |
| 11 | V | 64.5 | 23 | 20.6 | 64.6 |
| 11.5 | W | 66 | 24 | 21.0 | 65.9 |
| 12 | X | 67 | 25 | 21.4 | 67.2 |
How to Use the Ring Size Conversion Chart
If you know your size in one system, find it in the corresponding column and read across the row to see your size in any other system. If you have measured your finger using the paper strip method, find your circumference measurement in the rightmost column and read left to find your US size.
If your measurement falls between two rows, round up to the next size. A ring that is slightly too large is always more comfortable than one that is slightly too small, especially for daily wear.
How Accurate Are Ring Size Conversions Between Systems?
Ring size conversion is not perfectly precise between all systems. The US, UK, and European systems use different base measurements and different increment sizes, which means conversions are close approximations rather than exact matches. The differences are small enough, typically within a quarter size, that they are not noticeable in practice. However, if you are between sizes or need an exact fit, measuring your finger directly in millimeters (diameter or circumference) and providing that measurement to the jeweler is always more accurate than converting between systems.
Antoanetta rings are sized in the US system. If you know your size in a different system, use the table above to convert, and if you are uncertain, contact the designer with your millimeter measurement for personalized guidance.
When Should You Adjust Your Ring Size?
Wide bands (5mm or wider): Wide rings fit tighter than narrow rings at the same size because they cover more finger surface area. If ordering a wide band like the Marque at 6mm, consider sizing up by half a size from your standard measurement. The wide band sizing guide covers this in detail.
Comfort fit vs. standard fit: Rings with a comfort fit profile (a slightly domed interior) feel roomier than standard flat-interior rings at the same size. If you are sized for a standard fit ring and switch to comfort fit, the same size will feel slightly looser. The comfort fit guide explains when this matters.
Kinetic and articulated rings: Antoanetta's kinetic rings with moving links or rolling bands have unique sizing considerations. The movement components add subtle dimension that static sizing alone does not account for. The designer can advise on fit for specific kinetic designs when you reach out with your size and chosen ring.
Frequently Asked Questions About Ring Size Conversion
What is the average ring size for women?
In the US, the average women's ring size is approximately 6, though sizes 5 through 7 are the most commonly ordered range. Individual variation is wide, so always measure rather than assume.
Are European ring sizes the same as the circumference in millimeters?
Approximately, yes. European sizes are based on the inner circumference, so a European size 52 means the ring has roughly a 52mm circumference. Small rounding differences exist between the official European scale and raw circumference measurements.
My ring size is different on different fingers. Is that normal?
Completely normal. Ring sizes vary between fingers and between your left and right hands. Always measure the specific finger you plan to wear the ring on.
Can Antoanetta make sizes outside the standard range?
Because every ring is made to order, non-standard sizes may be available for certain designs. Contact the designer to discuss your specific needs.