Buying a ring online, planning a surprise proposal, or ordering a beautiful piece from an international jeweler can be a thrilling experience. However, it almost always comes with a major, headache-inducing hurdle: figuring out the correct ring size.
Unlike clothing, which often shares somewhat standardized global sizing, jewelry sizing is notoriously fragmented. The United States, the United Kingdom, Europe, and various Asian countries all utilize completely different measurement systems. A size that fits perfectly in New York might translate to a completely different dimension in London, Paris, or Tokyo. If you order the wrong size, you are left dealing with the hassle of returns, resizing, and potential delays—especially if the ring features intricate eternity settings or alternative materials that cannot be easily altered.
To save you from the guesswork and the stress, we have put together the ultimate guide to international ring sizes. Whether you are shopping for a diamond engagement ring, a simple gold band, or a vintage antique piece, this comprehensive breakdown will ensure your jewelry fits flawlessly, no matter where in the world it was crafted.
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Ring Size Conversion Chart
Match your size across US, UK, European and Japanese sizing.
US
Diameter (mm)
Circumference (mm)
UK
EU
Japan
3 14.0 44.2 F 44 4 4 14.9 46.8 H 46.5 7 5 15.7 49.3 J½ 49 9 6 16.5 51.9 L½ 51.5 11 7 17.3 54.4 N½ 54 14 8 18.2 57.0 P½ 56.5 16 9 18.9 59.5 R½ 59 18 10 19.8 62.1 T½ 61.5 20 11 20.6 64.6 V½ 64 22 12 21.4 67.2 X½ 66.5 24 13 22.2 69.7 Z½ 69 26
How to measure at home
- 1Wrap a strip of paper around the base of your finger and mark where it overlaps.
- 2Measure the strip in millimetres. That is your circumference.
- 3Find the closest circumference in the chart and read across.
Measure in the evening, when fingers are largest. Between two sizes, choose the larger one.
Sizes vary slightly by brand, so check the maker's own chart too.
Ring Size Conversion Chart
Match your size across US, UK, European and Japanese sizing.
| US | Diameter (mm) | Circumference (mm) | UK | EU | Japan |
|---|---|---|---|---|---|
| 3 | 14.0 | 44.2 | F | 44 | 4 |
| 4 | 14.9 | 46.8 | H | 46.5 | 7 |
| 5 | 15.7 | 49.3 | J½ | 49 | 9 |
| 6 | 16.5 | 51.9 | L½ | 51.5 | 11 |
| 7 | 17.3 | 54.4 | N½ | 54 | 14 |
| 8 | 18.2 | 57.0 | P½ | 56.5 | 16 |
| 9 | 18.9 | 59.5 | R½ | 59 | 18 |
| 10 | 19.8 | 62.1 | T½ | 61.5 | 20 |
| 11 | 20.6 | 64.6 | V½ | 64 | 22 |
| 12 | 21.4 | 67.2 | X½ | 66.5 | 24 |
| 13 | 22.2 | 69.7 | Z½ | 69 | 26 |
How to measure at home
- 1Wrap a strip of paper around the base of your finger and mark where it overlaps.
- 2Measure the strip in millimetres. That is your circumference.
- 3Find the closest circumference in the chart and read across.
Measure in the evening, when fingers are largest. Between two sizes, choose the larger one.
Sizes vary slightly by brand, so check the maker's own chart too.
Sizes vary slightly by brand, so check the maker's own chart too.
| US / Canada | UK / Australia | Europe (mm) | Asia / Japan | Inner Circumference (mm) | Inner Diameter (mm) |
|---|---|---|---|---|---|
| 4 | H | 46.5 | 4 | 46.8 | 14.9 |
| 4.5 | I | 47.5 | 5 | 47.8 | 15.2 |
| 5 | J | 49.0 | 7 | 49.3 | 15.7 |
| 5.5 | K | 50.0 | 8 | 50.3 | 16.0 |
| 6 | L | 51.5 | 10 | 51.9 | 16.5 |
| 6.5 | M | 52.5 | 11 | 52.9 | 16.8 |
| 7 | N | 54.0 | 13 | 54.4 | 17.3 |
| 7.5 | O | 55.0 | 14 | 55.5 | 17.7 |
| 8 | P | 56.5 | 15 | 57.0 | 18.1 |
| 8.5 | Q | 57.5 | 16 | 58.0 | 18.5 |
| 9 | R | 59.0 | 18 | 59.5 | 18.9 |
| 9.5 | S | 60.0 | 19 | 60.6 | 19.3 |
| 10 | T | 61.5 | 21 | 62.1 | 19.8 |
| 10.5 | U | 63.0 | 23 | 63.1 | 20.2 |
| 11 | V | 64.0 | 24 | 64.6 | 20.6 |
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Understanding the Different Ring Size Systems
To truly master the cheat sheet above, it helps to understand the logic—or lack thereof—behind the different global sizing systems.
The US and Canadian System
The North American system is perhaps the most widely recognized globally. It uses a numeric scale, typically ranging from size 3 to 13.5, including half and quarter sizes for a more precise fit. The numbers correspond to specific increments of inner circumference and diameter.
The UK and Australian System
If you are buying from a British or Australian jeweler, you will encounter an alphabetic sizing system. Sizes range from A to Z, utilizing both full and half letters (like A, ½A, B, ½B). While it looks completely different from the US system, it is simply mapping the same physical dimensions to letters. For example, a US size 7 is exactly the same physical ring as a UK size N.
The European System
Most of continental Europe, including countries like France, Germany, and Switzerland, uses a highly logical system based on the metric system. European ring sizes are simply the inner circumference of the ring measured in millimeters. Therefore, a size 54 ring has an inner circumference of exactly 54 millimeters. Some European countries also use an inner diameter scale, but circumference is the most common standard.
The Asian System (Japan and China)
Asian ring sizing can be slightly more complex because it varies by country. In Japan, the sizing system uses a numeric scale (typically 1 to 30) that is based on the inner diameter of the ring in millimeters, minus a specific constant. A Japanese size 10 is not the same as a US size 10. In China, jewelers often use the European circumference system, but you will also see local numeric scales. Always double-check the specific country's standard when shopping from Asian retailers.
[ebay-banner-H=250]How to Measure Your Ring Size at Home
If you do not have access to a professional jeweler's sizer, you can easily determine your size at home using a few simple methods.
The Paper Strip Method
Cut a strip of paper about half an inch wide and long enough to wrap around your finger. Wrap it around the base of the finger where the ring will sit. Mark the point where the paper overlaps. Lay the paper flat and measure the length in millimeters. Match this millimeter measurement to the inner circumference column in the HTML table above to find your global size.
The Existing Ring Method
If you are buying a gift and need to size a ring the person already owns, place the ring on a flat surface. Using a ruler with millimeter markings, measure the inside diameter of the ring from one inner edge to the opposite inner edge. Do not include the metal band itself in your measurement. Match this millimeter diameter to the table above.
[ebay-banner-H=250]Pro Tips for Getting the Perfect Fit
Getting the exact right size requires more than just looking at a chart. Keep these crucial tips in mind before you finalize your order:
- Time of Day Matters: Your fingers naturally swell throughout the day due to temperature changes, salt intake, and physical activity. Fingers are typically smallest in the early morning and largest in the late afternoon or evening. Always measure your finger at the end of the day for the most accurate, comfortable fit.
- Consider Your Knuckles: If your knuckle is significantly larger than the base of your finger, you will need to choose a size that can slide over the knuckle but still fits snugly at the base. You may need to size up by a half or full size, or look into rings with adjustable sizing beads.
- Account for Band Width: The wider the ring band, the tighter it will feel. If you are purchasing a wide band (8mm or wider), it is highly recommended to go up a half size from your measured narrow-band size.
- Temperature Fluctuations: Cold temperatures cause fingers to shrink, while heat causes them to expand. Avoid measuring your fingers when you are freezing cold or immediately after being out in the hot sun.
Final Thoughts
Navigating international ring sizes does not have to be a stressful experience. By keeping this conversion cheat sheet handy, understanding the underlying measurement systems, and taking the time to measure accurately at home, you can shop globally with total confidence. Bookmark this page, save the chart, and enjoy the process of finding your perfect piece of jewelry!