US to Japan ring size
Convert a US ring size to Japan in one step. Enter your US size and read the Japan equivalent, or use the full chart below.
US to Japan ring size chart
| US size | Japan size | Diameter (mm) |
|---|---|---|
| 3 | 4 | 14.1 |
| 3.5 | 5 | 14.5 |
| 4 | 7 | 14.9 |
| 4.5 | 8 | 15.3 |
| 5 | 9 | 15.7 |
| 5.5 | 10 | 16.1 |
| 6 | 12 | 16.5 |
| 6.5 | 13 | 16.9 |
| 7 | 14 | 17.3 |
| 7.5 | 15 | 17.7 |
| 8 | 16 | 18.1 |
| 8.5 | 17 | 18.5 |
| 9 | 18 | 19 |
| 9.5 | 19 | 19.4 |
| 10 | 20 | 19.8 |
| 10.5 | 22 | 20.2 |
| 11 | 23 | 20.6 |
| 11.5 | 24 | 21 |
| 12 | 25 | 21.4 |
| 12.5 | 26 | 21.8 |
| 13 | 27 | 22.2 |
US and Japan ring sizes describe the same physical bands with different labels. Because every size maps to a real inside diameter in millimetres, the conversion between US and Japan is exact, not an approximation. If you know the diameter of a ring that already fits, you can confirm both the US and the Japan size from the millimetre column.
The most looked-up conversions on this page: a US 6 is a Japan 12, a US 7 is a Japan 14, and a US 9 is a Japan 18. Women's rings most often fall around US 6 to 7, while men's rings cluster near US 9 and above.
If your size sits between two rows, size up. It is easier to pad or resize a ring that is a touch loose than to stretch one that will not clear your knuckle. For a hands-on check, print the true-scale ring sizer and match a ring you own.
Common questions
What is a US 7 ring size in Japan?
A US 7 ring is a Japan 14. Both labels describe the same band with an inside diameter of 17.3 mm.
How do I convert a US ring size to Japan?
Find your US size in the chart and read across to the Japan column, or use the converter above. Both point to the same physical band diameter, so the conversion is exact.
Is a US ring size the same as Japan?
No, the labels differ, but the bands are the same physical sizes. The chart lines up each US size with its Japan equivalent and the diameter in millimetres.
What if my size falls between two values?
Choose the larger size. A slightly loose ring can be resized or padded, but a ring that is too small will not pass the knuckle.
Last reviewed and updated on July 2, 2026. Conversion tables are checked against published international sizing standards.