One size, several naming systems
Understand what changes when a ring size crosses borders.
Regional labels can differ even when the physical ring is similar. Keep the original label, measurement method, and converted direction together for a more useful review.
Fit, wear & care—considered together
A clearer decision, with the important context kept beside it
Ring-size labels are different names for nearby physical dimensions. This guide shows what each system means before you use the converter.
Use this page when
- You want to understand a chart mismatch before selecting a size.
- You need to explain a known size to a jeweler in another country.
Pause this route when
- You have no original system or physical measurement.
- You need a full converter result without opening the working tool.
Where this choice often matters
- Buying from an international collection.
- Translating a family ring’s record for a new custom piece.
Compare the details
System labels and their useful anchor
Use the official standard context for measurement, then the approved Leyloon table for actual mappings.
| System | Label style | Useful anchor | Caution |
|---|---|---|---|
| US / Canada | Numbers and fractions | Governed table row | Not a millimeter value |
| UK / Australia | Letters and fractions | Governed table row | Charts may round differently |
| EU | Numeric convention | Inside-circumference context | State the table used |
| Japan | Numeric scale | Governed crosswalk | Preserve original label |
Ring-size reference chart
Compare named sizes with inside measurements
Keep your original system and maker’s chart. This table is a comparison aid, not a universal fit promise.
| US & Canada | UK, Europe & Australia | Asia | Inside diameter | Inside circumference |
|---|---|---|---|---|
| 3 | F | 4 | 14.1 mm | 44.3 mm |
| 3.5 | G | — | 14.5 mm | 45.6 mm |
| 4 | H | 7 | 14.9 mm | 46.8 mm |
| 4.5 | I | 8 | 15.3 mm | 48.1 mm |
| 5 | J | 9 | 15.7 mm | 49.3 mm |
| 5.5 | K | 10 | 16.1 mm | 50.6 mm |
| 6 | L | 11 | 16.5 mm | 51.8 mm |
| 6.5 | M | 13 | 16.9 mm | 53.1 mm |
| 7 | N | 14 | 17.3 mm | 54.3 mm |
| 7.5 | O | 15 | 17.7 mm | 55.6 mm |
| 8 | P | 16 | 18.1 mm | 56.9 mm |
| 8.5 | Q | 17 | 18.5 mm | 58.1 mm |
| 9 | R | 18 | 19.0 mm | 59.7 mm |
| 9.5 | S | 19 | 19.4 mm | 60.9 mm |
| 10 | T | 20 | 19.8 mm | 62.2 mm |
| 10.5 | U | 22 | 20.2 mm | 63.5 mm |
| 11 | V | 23 | 20.6 mm | 64.7 mm |
| 11.5 | W | 24 | 21.0 mm | 66.0 mm |
| 12 | X | 25 | 21.4 mm | 67.2 mm |
| 12.5 | Y | 26 | 21.8 mm | 68.5 mm |
| 13 | Z.5 | 27 | 22.2 mm | 69.7 mm |
| 13.5 | Z1 | — | 22.6 mm | 71.0 mm |
Reviewed 2026-08-25. Source reference: GIA ring-size guide. This table follows GIA’s US and Canada, UK/Europe/Australia, and Asia columns; blank cells are not listed by GIA. Leyloon uses the nearest physical row without interpolation and keeps your original measurement beside it.
Keep your direction organised
The complete choice groups for this decision
These groups support this page’s promise: Ring-size labels are different names for nearby physical dimensions. This guide shows what each system means before you use the converter. Use them to compare what belongs together; make and keep your editable choices in the working path that follows.
What are you trying to understand?
Choose one direction.
- A country labelSee how it maps physically.
- A diameter or circumferenceKeep measurement type visible.
- Two charts disagreeCompare sources and nearby rows.
- A maker-specific chartPreserve that chart with the note.
What can confirm the conversion?
Keep every direction that fits.
- Measure the existing ringAdds inside diameter.
- Check the intended fingerAdds personal fit.
- Confirm band widthAdds design context.
- Professional gaugeTests the physical fit.
Questions worth asking
Open the concern that sounds like yours
Each answer stays within this page’s promise—Ring-size labels are different names for nearby physical dimensions. This guide shows what each system means before you use the converter.—without making the next step feel heavier than it needs to be.
Which system is most accurate?
The physical measurement and correct fit matter more than the label; each system names table positions differently.
Why not use a formula for every system?
Named scales are governed table mappings, not all simple formulas.
What if my size falls between chart rows?
Show both nearby rows and take the band and wearer context into review.
Ready when you are
Carry this direction into your design
Leyloon can keep these choices together while you continue. Every detail stays editable. For this page, that means: Ring-size labels are different names for nearby physical dimensions. This guide shows what each system means before you use the converter.
- Original label and physical comparisonNeeded before the direction is complete
- Optional chart or receipt referenceKeep it open if you are still deciding
- Intended widthA useful next question
- Table mismatch or nearby rowsKeep it open if you are still deciding
A visual map of this brief
See what stays known—and what remains open
This route begins with “Separate the name of the size from the physical ring it describes.” The next choices stay grouped, editable, and connected to that same Atelier brief.
- Ring you are sizingChoose the ring context so the measurement stays attached to the right width, profile, and finger.
- What measurement do you have?Keep the method with the number. The working tool above can help compare it without replacing the maker's final fit check.
- Band width or stackChoose the planned contact width. Exact millimeters stay editable.
- What could change the fit?Choose the closest context. You can add the exact measurements privately in Atelier.
Start with what matters on this page
Keep the measurement with the ring it belongs to
Choose how you measured and the ring context. The number stays private, and Atelier carries the method, width, and fit notes together.Published customer proof
Real experiences, kept separate from promises
Only approved purchase-linked reviews appear here. An illustrative scene is never presented as a customer, and one person’s experience is never treated as a promise for another piece.See what Leyloon customers have shared
Read recent shop reviews on Etsy, then come back when you are ready to shape your own fit and jewelry direction.
These reviews reflect individual Leyloon service experiences. Your fit and jewelry direction and quote request are reviewed on their own.