Buying a ring online without trying it first is one of the more nerve-wracking parts of online jewelry shopping. Get it wrong and the piece you've been wanting doesn't fit. This guide gives you two methods for measuring at home, a complete Japanese ring size (号) chart, and some practical advice for making the right call.
The String Method
This is the most common home measurement method, and it's accurate enough for most purposes.
- Cut a thin strip of string, thread, or a narrow strip of paper — about 15cm long.
- Wrap it snugly around the base of the finger you're sizing for. Snug, not tight — you should be able to slip it off without force.
- Mark or pinch the string where it overlaps to form a complete circle.
- Lay the string flat and measure the length from one end to the mark. This is your finger's circumference in millimeters.
- Use the size chart below to find your Japanese ring size (号).
The Paper Strip Method
Slightly more accurate because paper holds its shape better than thread.
- Cut a strip of paper about 6mm wide and 10cm long.
- Wrap it around your finger at the base. Make sure it can slide over your knuckle — a ring that fits the base of your finger but won't clear the knuckle is useless.
- Mark where the paper overlaps.
- Flatten and measure with a ruler in millimeters.
03Japanese Ring Size (号) Chart
| Japan Size (号) | Circumference (mm) | Inner Diameter (mm) |
|---|---|---|
| 1号 | 40.8 | 13.0 |
| 2号 | 41.9 | 13.3 |
| 3号 | 42.9 | 13.7 |
| 4号 | 44.0 | 14.0 |
| 5号 | 45.0 | 14.3 |
| 6号 | 46.1 | 14.7 |
| 7号 | 47.1 | 15.0 |
| 8号 | 48.2 | 15.3 |
| 9号 | 49.2 | 15.7 |
| 10号 | 50.3 | 16.0 |
| 11号 | 51.3 | 16.3 |
| 12号 | 52.4 | 16.7 |
| 13号 | 53.4 | 17.0 |
| 14号 | 54.5 | 17.3 |
| 15号 | 55.5 | 17.7 |
| 16号 | 56.5 | 18.0 |
| 17号 | 57.6 | 18.3 |
| 18号 | 58.6 | 18.7 |
| 19号 | 59.7 | 19.0 |
| 20号 | 60.7 | 19.3 |
| 21号 | 61.8 | 19.7 |
| 22号 | 62.8 | 20.0 |
| 23号 | 63.9 | 20.3 |
| 24号 | 64.9 | 20.7 |
| 25号 | 66.0 | 21.0 |
| 26号 | 67.0 | 21.3 |
| 27号 | 68.1 | 21.7 |
| 28号 | 69.1 | 22.0 |
| 29号 | 70.2 | 22.3 |
| 30号 | 71.2 | 22.7 |
04Tips for Getting It Right
Timing matters
Fingers are larger in the evening than in the morning, and larger in warm weather than cold. If you want a comfortable everyday fit, measure in the afternoon or evening. If you run cold or your fingers tend to be slim, measure when warm.
Account for the knuckle
If your knuckle is noticeably larger than the base of your finger, size for the knuckle. A ring that fits your knuckle but is loose at the base is easier to live with than one that won't go on at all. A small ring adjuster can compensate for the extra space at the base.
Wide bands fit tighter
A wide band ring — anything over about 6mm — will feel tighter than a slim band at the same size. If you're ordering a wide ring, go up half a size from your measured size.
Measure twice
Do both methods and take the average. Measure the same finger two or three times and use the most consistent result.
What to Do If You're Between Sizes
If your circumference falls between two sizes, consider which finger the ring is for and how you want it to fit. A ring worn on the index finger is typically worn a little looser. A ring worn on the middle finger or pinky often fits better snug.
When in doubt, go up half a size. A slightly loose ring is easier to resize or adjust than one that won't go on.
Contacting Us
If you're unsure about sizing for a specific piece, reach out before purchasing. Because many MRSUPPLY rings are One of a Kind, we can't always guarantee a specific piece will still be available, but we can give you accurate sizing information for any ring listed in our shop.
contact@mrsupply.store