International charts
Japan ring size chart
Japanese ring sizes are whole numbers with finer steps than US half sizes — and published JP tables do not fully agree with each other. This page gives JP numbers derived from the millimetre measurements in this site's own chart, labelled approximate, so you can convert a JP size to US, UK or EU without pretending the JP ladder is exact.
How the JP number works
Whole numbers only
Unlike the US system, Japan does not use half sizes. Each JP step is about 1 mm of circumference — finer than a US half-size step (about 1.3 mm) — which is why JP numbers run higher: the same finger is roughly JP 14 where it is US 7.
The −40 rule
The trade convention behind JP tables is simple: JP ≈ inner circumference (mm) − 40. A 44 mm circumference is about JP 4; a 54 mm circumference is about JP 14; a 70 mm circumference is about JP 30. Rounding and table differences move individual rows by about one JP step.
Why JP is labelled approximate here
Compare any two published JP tables and they disagree at some rows — US 6 appears as JP 11 on some and JP 12 on others, for example. That disagreement is exactly why this site labels UK approximate too, and why the diameter and circumference columns below matter more than the JP column.
Japan chart — derived from millimetres
| JP (approx.) | US | UK (approx.) | EU | Inner diameter (mm) | Inner circumference (mm) |
|---|---|---|---|---|---|
| 4 | 3 | F | 44 | 14.07 | 44.2 |
| 6 | 3.5 | G | 46 | 14.48 | 45.5 |
| 7 | 4 | H | 47 | 14.88 | 46.7 |
| 8 | 4.5 | I | 48 | 15.29 | 48.0 |
| 9 | 5 | J | 49 | 15.70 | 49.3 |
| 11 | 5.5 | K | 51 | 16.10 | 50.6 |
| 12 | 6 | L | 52 | 16.51 | 51.9 |
| 13 | 6.5 | M | 53 | 16.92 | 53.2 |
| 14 | 7 | N | 54 | 17.32 | 54.4 |
| 16 | 7.5 | O | 56 | 17.73 | 55.7 |
| 17 | 8 | P | 57 | 18.14 | 57.0 |
| 18 | 8.5 | Q | 58 | 18.54 | 58.2 |
| 20 | 9 | R | 60 | 18.95 | 59.5 |
| 21 | 9.5 | S | 61 | 19.35 | 60.8 |
| 22 | 10 | T | 62 | 19.76 | 62.1 |
| 23 | 10.5 | U | 63 | 20.17 | 63.4 |
| 25 | 11 | V | 65 | 20.57 | 64.6 |
| 26 | 11.5 | W | 66 | 20.98 | 65.9 |
| 27 | 12 | X | 67 | 21.39 | 67.2 |
| 29 | 12.5 | Y | 69 | 21.79 | 68.5 |
| 30 | 13 | Z | 70 | 22.20 | 69.7 |
| 31 | 13.5 | Z+1 | 71 | 22.61 | 71.0 |
How to use this table: find your US size (or your millimetre measurement) in the row, read the JP number, then give the seller the diameter and circumference as well. If the seller's chart says a different JP number for the same millimetres, the millimetres win.
Converting a JP size you already have
- JP to millimetres: add 40 to the JP number to estimate the circumference — JP 14 is about 54 mm around, JP 20 is about 60 mm around. Then check that circumference against the table above.
- JP to US: find the JP number in the table and read across to the US column. Because JP steps are finer, a JP number between two US rows means you sit between sizes — size up for comfort, as with any between-sizes reading.
- Buying from Japan: Japanese sellers size by their own JP table. Send them your millimetre circumference (measured in the evening, with warm hands) and ask them to confirm the JP size from it, rather than converting it yourself and ordering on the converted label alone.
Limitations
JP sizes on this page are derived approximations, not a published Japanese standard quoted verbatim: Japan's JP numbering is a trade convention, and published tables disagree by about ±1 JP at some rows. No JP value here should be treated as exact, and a JP purchase should always be confirmed with the seller using the diameter and circumference in millimetres.
Related guides
- International ring size chart
The full US / UK / EU / India chart this JP table is derived from.
- Ring size converter
Convert a US, UK, EU or India size — and a millimetre measurement — between systems.
- Large ring sizes
Sizes above US 13.5, as labelled approximations with millimetres.
- How to measure a finger for a ring
Get the circumference in millimetres that JP conversion actually needs.