Ring Size Guide: mm to EU, US and UK
Last updated: 15 September 2026
How are Loretana rings sized?
Loretana rings are sized by inner diameter in millimetres. Fixed-size rings come in four sizes — 16.5, 17.3, 18.1 and 18.9 mm — which correspond exactly to US 6, 7, 8 and 9. A 17.3 mm ring measures 17.3 millimetres across the inside.
Every product page shows both numbers, for example 17.3 mm (US 7), so you can order by whichever system you know. Use the table below to convert to EU or UK.
Ring size conversion table
Inner circumference is the diameter multiplied by pi. EU and UK equivalents are approximate, because those systems round to their own steps.
| Loretana (mm diameter) | Inner circumference | US | EU (approx.) | UK (approx.) |
|---|---|---|---|---|
| 16.5 | 51.8 mm | 6 | 52 | L½ |
| 17.3 | 54.4 mm | 7 | 54 | N½ |
| 18.1 | 56.9 mm | 8 | 57 | P½ |
| 18.9 | 59.4 mm | 9 | 59 | R½ |
I know my Baltic size. Which Loretana size is that?
Ring sizes in Lithuania, Latvia and Estonia are usually quoted as a whole or half millimetre of diameter. Our four sizes fall between some of those steps, so round to the nearest one:
- Baltic 16 or 16.5 → 16.5 mm (US 6)
- Baltic 17 or 17.5 → 17.3 mm (US 7)
- Baltic 18 → 18.1 mm (US 8)
- Baltic 18.5 or 19 → 18.9 mm (US 9)
How do I measure my ring size at home?
Method 1: measure a ring you already wear
- Choose a ring that fits the finger you have in mind.
- Lay it flat and measure straight across the inside, edge to edge, with a ruler.
- Match that measurement in millimetres to the nearest diameter in the table.
A ring measuring 17 mm across the inside is closest to 17.3 mm (US 7).
Method 2: measure your finger
- Wrap a strip of paper or a piece of string around the base of the finger.
- Mark where it overlaps and measure the length in millimetres. That is your inner circumference.
- Find the closest circumference in the table above, or divide by 3.14 to get the diameter.
A finger measuring 53 mm around falls between two sizes; take the larger, 17.3 mm (US 7).
When should I measure?
Fingers change size during the day and with the weather. For the most reliable result:
- Measure at the end of the day, when fingers are at their largest.
- Avoid measuring when your hands are cold, which makes fingers thinner.
- Measure the same finger on the same hand you intend to wear the ring on. The dominant hand is often half a size larger.
What if I am between sizes?
Choose the larger size. A ring that is slightly loose can still be worn; one that is too tight cannot. If your knuckle is noticeably wider than the base of the finger, size to the knuckle so the ring passes over it.
Which Loretana rings are adjustable?
Several designs come as an open, adjustable band instead of a fixed size. These fit most fingers and are a safe choice when you are buying a gift and do not know the size, including the engravable heart and rectangle rings, the clover and birthstone rings, the geometric ring, the hammered teardrop ring and the twisted wave ring.
Frequently asked questions
Is ring size the diameter or the circumference?
Loretana sizes are the inner diameter in millimetres. Circumference is the distance around the inside, which is roughly 3.14 times the diameter.
What is the most common ring size?
The middle of our range — 17.3 mm (US 7) and 18.1 mm (US 8) — fits the majority of women's hands. If you are buying a gift and cannot measure, an adjustable design removes the risk entirely.
Can a Loretana ring be resized?
Fixed-size rings are not resized. Choose from the four sizes above, or pick one of the adjustable open-band designs.
How do I find out someone's size for a gift?
Borrow a ring they already wear on the right finger and measure it with method 1, or choose an adjustable design and avoid the question entirely.
Should a ring feel tight?
It should pass the knuckle with gentle resistance and sit without pinching. If it leaves a deep mark or will not turn on the finger, it is too small.