This ring-size page is best for cross-system comparison. You may know your size in US format while a seller lists UK letters, or you may have a rough inner-diameter measurement in millimeters and want to estimate EU, JP, or CH sizing. The page helps align those systems quickly.
It is especially useful for international jewelry shopping, cross-border marketplaces, gift planning, and early sizing conversations. The point is not to pretend there is one perfectly universal number. The point is to narrow the likely range before you confirm the final fit with a brand chart or real try-on.
Enter the size in the format of the selected source system. US, EU, JP, CH, and millimeter diameter use numeric input. UK uses a letter input. The current page works best with a single whole UK letter rather than more detailed half-size conventions.
The source system tells the page how to interpret the entered value. The same number can mean very different things in US sizing versus millimeter diameter, so this selection matters a lot.
The current page supports US Canada, UK Australia, European, Japanese, Chinese, Swiss, and millimeter inner diameter.
UK sizing is entered as a letter here, and it works best with a single whole letter such as K or M.
No. The conversions are formula-based approximations, so they are better for comparison than for brand-specific final sizing.
It shows all supported systems at once for side-by-side comparison.
Convert ring sizes between different international standards.