Use a ring that already feels right
Measure an existing ring while preserving the details that make it useful.
Choose a ring worn on the intended finger and hand, measure its inside diameter, and record the unit. A similar-looking ring worn elsewhere may lead to the wrong direction.
Fit, wear & care—considered together
A clearer decision, with the important context kept beside it
Measure straight across the empty interior of a round ring that truly fits the intended finger—never across the outside metal.
Use this page when
- You can identify the source ring’s usual hand and finger.
- The ring is round and its inside edge is unobstructed.
Pause this route when
- The ring is bent, oval, adjustable, or has an unusual inner profile.
- The source ring belongs on a different finger or only fits under unusual conditions.
Where this choice often matters
- Discreetly checking a partner’s ring for a proposal.
- Recreating the fit of a favorite everyday ring.
Compare the details
Four checks before reading the ruler
Show the source ring, ruler, and measurement line in one uncluttered diagram.
| Check | Correct | Wrong | Why it matters |
|---|---|---|---|
| Edge | Inner edge to inner edge | Outside edge | Outside metal overstates diameter |
| Line | Straight through the center | Off-center chord | A chord understates diameter |
| Shape | Round interior | Bent or oval | One axis cannot stand for the ring |
| Identity | Known intended finger | Similar-looking ring | Finger context can change the size |
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: Measure straight across the empty interior of a round ring that truly fits the intended finger—never across the outside metal. Use them to compare what belongs together; make and keep your editable choices in the working path that follows.
What is true about the ring?
Keep every direction that fits.
- Correct intended fingerYou know where it is normally worn.
- Round interiorNo bend or oval distortion.
- Comfortably fits nowNot only during unusual swelling.
- One detail is uncertainKeep the result as an estimate.
How will you measure it?
Choose one direction.
- Millimeter rulerAlign through the true center.
- Non-damaging caliperRead the inside opening gently.
- Jeweler’s mandrelUse the correct profile and setting care.
- Calibrated print circlesPass the 50 mm scale check first.
Questions worth asking
Open the concern that sounds like yours
Each answer stays within this page’s promise—Measure straight across the empty interior of a round ring that truly fits the intended finger—never across the outside metal.—without making the next step feel heavier than it needs to be.
Can I use a phone ruler?
Only if it is physically calibrated; a real millimeter ruler or jeweler’s mandrel is a clearer reference.
What if the ring sits between marks?
Record the actual millimeter reading and show both nearby governed size rows.
Can Leyloon use a photo?
A photo can explain the reference, but it needs a reliable scale and does not replace the actual inside measurement.
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: Measure straight across the empty interior of a round ring that truly fits the intended finger—never across the outside metal.
- Inside diameter in millimetersNeeded before the direction is complete
- Optional permitted photo of the source ring and rulerKeep it open if you are still deciding
- Source-ring width and intended new widthA useful next question
- Usual hand, finger, shape, and confidenceKeep 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 “Use a ring that already fits, but measure the part that matters.” 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.