Ring Size Converter and Chart (US, UK, EU, Japan, India)
Convert ring sizes between US, UK, Europe (ISO), Japan, India, Italy and Switzerland, or find your size from the diameter or circumference in mm.
| System | Size |
|---|---|
| United States, Canada | β |
| UK, Ireland, Australia | β |
| Europe (ISO 8653) | β |
| Italy, Spain, Switzerland | β |
| Japan, China, Korea | β |
| India | β |
| Inside diameter | β |
| Inside circumference | β |
- Wrap a strip of paper or string around the base of the finger, mark where it overlaps and measure the length in mm: that is the circumference.
- Or measure the inside diameter of a ring that fits you well, from edge to edge, in mm.
- Measure at the end of the day, when fingers are larger, and make sure the ring can still pass over the knuckle.
Ring size chart
| US | UK | ISO | Γ mm | JP | IN | IT/ES/CH |
|---|
What it does
Every country has its own ring sizes. The ISO 8653 standard used in most of Europe gives the inside circumference in millimetres; Italy, Spain and Switzerland use the circumference minus 40; the US and Canada use numbers with quarter sizes, each 0.8128 mm of diameter apart; the UK, Ireland and Australia use letters, 1.25 mm of circumference apart (BS 6820). Japan, China and India use number scales that do not follow a formula. The converter goes through the inside diameter to translate between all of them.
How to use it
- Choose the system you know, or the diameter or circumference if you measured.
- Pick your size or type the measurement in mm or inches.
- See the size in every system, plus the diameter and circumference, and check the chart below.
The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.
Frequently asked questions
What is a US size 7 ring in mm?
A US size 7 ring has an inside diameter of 17.3 mm and a circumference of 54.4 mm. That is N½ in the UK, about 54 in the ISO system, 14 in Italy and Switzerland, and 14 in Japan and India.
How do I convert a UK ring size to a US size?
Each UK letter is 1.25 mm of circumference, a little less than half a US size. L½ is US 6, N½ is US 7 and P½ is US 8.
What if I am between two sizes?
Choose the larger size, especially for wide bands, which feel tighter. Fingers swell in the heat and at the end of the day.
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