Ring Size Guide
Find your fit
Every By Lucia ring is sized to US standards, with half sizes on selected styles. Use the chart to convert from your local size, or measure at home in two minutes.
Size conversions
| US / Canada | UK · AUS · NZ | Europe | Diameter (mm) |
|---|---|---|---|
| 2 | D½ | 41.5 | 13.2 |
| 2½ | E½ | 42.7 | 13.6 |
| 3 | F½ | 44.2 | 14.0 |
| 3½ | G½ | 45.5 | 14.4 |
| 4 | H | 47 | 14.9 |
| 4½ | I | 48 | 15.3 |
| 5Popular | J½ | 49 | 15.7 |
| 5½ | K½ | 50.5 | 16.1 |
| 6 | L½ | 51.5 | 16.5 |
| 6½ | M½ | 53 | 16.9 |
| 7 | N½ | 54 | 17.3 |
| 7½ | O½ | 55.5 | 17.7 |
| 8 | P½ | 57 | 18.1 |
| 8½ | Q½ | 58 | 18.5 |
| 9 | R½ | 59.5 | 18.9 |
| 9½ | S½ | 61 | 19.4 |
| 10 | T½ | 62 | 19.8 |
| 10½ | U½ | 63.5 | 20.2 |
| 11 | V½ | 64.5 | 20.6 |
| 12 | Y | 67 | 21.4 |
Europe shown as inner circumference (mm). Diameter is the universal reference — the most reliable number to match.
How to measure at home
String or paper
- Cut a thin strip of paper or a length of string.
- Wrap it snugly around the base of your finger — below the knuckle.
- Mark where it overlaps, lay it flat, and measure in millimetres.
- Match that to the Europe (circumference) column.
Measure a ring you own
- Pick a ring that fits the right finger well.
- Measure the inside diameter straight across, in millimetres.
- Match that to the Diameter (mm) column.
- That's your size — in every system.
A few notes on fit
- Between two sizes? Half sizes are available on selected styles — choose the half size where offered. Otherwise size up: a fraction loose is comfortable; too tight isn't.
- Measure warm, at the end of the day — fingers are smallest in the morning and in the cold.
- Wide or stacked bands sit tighter; consider going up half a size.
Still unsure? Email contact@bylucia.co and a member of the team will help you find your size.
Conversions are approximate and provided as a guide. Small production tolerances apply — if you're ordering internationally and unsure, measure at home or check with a local jeweller before purchasing.