In Japan, ring sizes are expressed in gō (号). The scale is different from US numbers, UK letters and the European circumference in millimetres, so visitors choosing a ring in Japan, or anyone ordering a Japanese ring for family overseas, often wonder "what size am I in Japan?" This page gives a quick conversion chart and tips for telling a Japanese store your size.
What a Japanese "gō" means
The number is based on the inner circumference of the ring. Size 1 has an inner diameter of about 13.0 mm, and each size up adds roughly 1/3 mm to the diameter (about 1.05 mm to the circumference). Many women in Japan wear wedding rings around sizes 7–11 and men around 13–19, but finger shape and season change things, so the reliable way is to be measured with a ring gauge in the store. See how to measure your ring size (gō).
Conversion chart (Japan 3–25)
US sizes are rounded to the nearest quarter and UK sizes to the nearest half letter. The circumference in millimetres (the EU/ISO notation) is the most precise reference, so when in doubt, tell the store your size in mm.
| Japan (gō) | Circumference (mm / EU・ISO) | US / Canada | UK / Australia |
|---|---|---|---|
| 3 | 42.9 mm | 2½ | E |
| 4 | 44.0 mm | 3 | F |
| 5 | 45.0 mm | 3¼ | G |
| 6 | 46.1 mm | 3¾ | G½ |
| 7 | 47.1 mm | 4¼ | H½ |
| 8 | 48.2 mm | 4½ | I½ |
| 9 | 49.2 mm | 5 | J |
| 10 | 50.3 mm | 5½ | K |
| 11 | 51.3 mm | 5¾ | L |
| 12 | 52.4 mm | 6¼ | L½ |
| 13 | 53.4 mm | 6½ | M½ |
| 14 | 54.5 mm | 7 | N½ |
| 15 | 55.5 mm | 7½ | O |
| 16 | 56.5 mm | 7¾ | P |
| 17 | 57.6 mm | 8¼ | Q |
| 18 | 58.6 mm | 8¾ | Q½ |
| 19 | 59.7 mm | 9 | R½ |
| 20 | 60.7 mm | 9½ | S½ |
| 21 | 61.8 mm | 10 | T |
| 22 | 62.8 mm | 10¼ | U |
| 23 | 63.9 mm | 10¾ | V |
| 24 | 64.9 mm | 11 | V½ |
| 25 | 66.0 mm | 11½ | W½ |
Values are calculated from each system's standard definitions and are a guide only. Fit changes with band width and thickness, so always try the ring on or use a ring gauge before buying.
You can see the rings in person at a store near you.Find a store near you
If you only know your overseas size
- Convert to millimetres. Whatever notation you use (US, UK, Hong Kong, Taiwan), the inner circumference in mm is understood in any Japanese store.
- Bring a ring that fits. The store can measure its inner diameter and give you the Japanese size.
- Go slightly larger for wide bands. Designs 3 mm or wider feel tighter at the same size; trying half a size to one size up is common.
- Fingers change during the day. They swell in the evening and in summer. Trying rings on more than once, at different times, gives a safer result.
Resizing
Most Japanese bridal brands offer resizing after purchase (free periods, number of times and excluded designs vary by brand). If you are buying from overseas, ask before purchase how resizing works once you are home: whether the ring must be sent to a store in Japan, or whether an overseas stockist can handle it. See the ring resizing guide.
Choosing a ring in Japan
Reservations, language support, tax-free shopping and delivery are covered in our guide for visitors buying rings in Japan. Find stores by prefecture in the store list.