Ring Size Conversion Table
The Japanese ring size scale increases by 1/3 mm (0.333…mm) per size number. This table shows ring sizes for various countries.
To find your accurate ring size, we recommend measuring your finger’s circumference directly with a tape measure, or You can also get an accurate ring size by wrapping a thin strip of paper around your finger, marking where it overlaps, and then measuring the length of the paper with a ruler. This allows you to determine your size based on your finger’s circumference, which we recommend.
Please note that fingers shrink slightly on colder days. Finger size can also vary due to swelling.
A wide ring may feel tighter than a thin ring of the same size, so consider the width of rings you normally wear when selecting your size.For example, if a thin ring is size 11(JCS), a wider ring will often fit best around size 12(JCS) for the same finger.
Choosing the size based on your finger circumference can help ensure the best fit.
*Ring sizes for countries other than Japan are approximate values.
*For smartphones, turn your screen horizontally to view the table more easily.
| 日本の指輪 サイズ （JCS規格） Japan Sizes | リング直径/ Ring Diameter (mm) | 指回り/ Finger Circumference (mm) | USA Sizes | Australian /British Sizes | Hong Kong /Singapore Sizes | ISO/JIS Sizes |
|---|---|---|---|---|---|---|
| 0号 | 12.666 | 39.8 | US 1.3 | B-C | – | 40 |
| 1号 | 13 | 40.8 | US 1.7 | C-D | – | 41 |
| 2号 | 13.333 | 41.9 | US 2.1 | D | 4 | 42 |
| 3号 | 13.666 | 42.9 | US 2.6 | E | 5 | 43 |
| 4号 | 14 | 44 | US 3 | F | 6 | 44 |
| 5号 | 14.333 | 45 | US 3.4 | G | 7 | 45 |
| 6号 | 14.666 | 46.1 | US 3.8 | G-H | 8 | 46 |
| 7号 | 15 | 47.1 | US 4.3 | H-I | 9-10 | 47 |
| 8号 | 15.333 | 48.2 | US 4.7 | I-J | 10 | 48 |
| 9号 | 15.666 | 49.2 | US 5.1 | J-K | 11 | 49 |
| 10号 | 16 | 50.3 | US 5.5 | Ｋ | 11-12 | 50 |
| 11号 | 16.333 | 51.3 | US 5.8 | L | 12-13 | 51 |
| 12号 | 16.666 | 52.4 | US 6.1 | M | 14 | 52 |
| 13号 | 17 | 53.4 | US 6.5 | N | 14-15 | 53 |
| 14号 | 17.333 | 54.5 | US 6.9 | O | 16 | 54 |
| 15号 | 17.666 | 55.5 | US 7.3 | O-P | 17 | 55 |
| 16号 | 18 | 56.6 | US 7.7 | P | 17-18 | 56 |
| 17号 | 18.333 | 57.6 | US 8.2 | Q | 18-19 | 57 |
| 18号 | 18.666 | 58.6 | US 8.6 | R | 19-20 | 58 |
| 19号 | 19 | 59.7 | US 9 | R-S | 20-21 | 59 |
| 20号 | 19.333 | 60.7 | US 9.4 | S-T | 21-22 | 60 |
| 21号 | 19.666 | 61.8 | US 9.8 | T | 22-23 | 61 |
| 22号 | 20 | 62.8 | US 10.2 | U | 23-24 | 62 |
| 23号 | 20.333 | 63.8 | US 10.6 | V | 24-25 | 63 |
| 24号 | 20.666 | 64.9 | US 11.1 | W | 25 | 64 |
| 25号 | 21 | 65.9 | US 11.5 | W-X | 26 | 65 |
| 26号 | 21.333 | 67.0 | US 11.9 | X-Y | 27-28 | 66 |
| 27号 | 21.666 | 68.0 | US 12.3 | Y-Z | 28 | 67 |
| 28号 | 22 | 69.1 | US 12.7 | Z | 29 | 68 |
| 29号 | 22.333 | 70.1 | US 13.1 | Z+1 | 30 | 69 |
| 30号 | 22.666 | 71.2 | US 13.6 | Z+2 | – | 70 |
| 31号 | 23 | 72.2 | US 14 | Z+3 | – | 71 |
| 日本の指輪 サイズ （JCS規格） Japan Sizes | リング直径/ Ring Diameter (mm) | 指回り/ Finger Circumference (mm) | USA Sizes | Australian /British Sizes | Hong Kong /Singapore Sizes | ISO/JIS Sizes |