Find your ring size
Three ways to measure, depending on what you have to hand. The result gives the French size, used by jewellers in France, and its US and UK equivalents.
Wrap a string or a strip of paper around the base of your finger, mark where it meets, then measure the length flat with a ruler.
With a ruler, measure the inside diameter of a ring that fits you well, from one inner edge to the other.
Place a ring that fits you on the screen, then adjust the circle until it follows its inner edge exactly.
Screen not calibrated: the size shown is approximate. Screen calibrated to real size.
Hold a bank card (or any card of the same size) against the screen, then move the slider until the rectangle is exactly as wide as the card.
Your size
French size
- US size
- UK size
- Inside diameter
Enter a measurement to see your size.
This measurement is outside common ring sizes. Check that it is in millimetres.
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Ring size conversion chart
| French size | Circumference | Inside diameter | US size | UK size |
|---|---|---|---|---|
| 44 | 44 mm | 14.0 mm | 3 | F |
| 45 | 45 mm | 14.3 mm | 3.25 | G |
| 46 | 46 mm | 14.6 mm | 3.75 | H |
| 47 | 47 mm | 15.0 mm | 4 | H½ |
| 48 | 48 mm | 15.3 mm | 4.5 | I½ |
| 49 | 49 mm | 15.6 mm | 5 | J |
| 50 | 50 mm | 15.9 mm | 5.25 | K |
| 51 | 51 mm | 16.2 mm | 5.75 | L |
| 52 | 52 mm | 16.6 mm | 6 | L½ |
| 53 | 53 mm | 16.9 mm | 6.5 | M½ |
| 54 | 54 mm | 17.2 mm | 6.75 | N½ |
| 55 | 55 mm | 17.5 mm | 7.25 | O |
| 56 | 56 mm | 17.8 mm | 7.5 | P |
| 57 | 57 mm | 18.1 mm | 8 | Q |
| 58 | 58 mm | 18.5 mm | 8.5 | Q½ |
| 59 | 59 mm | 18.8 mm | 8.75 | R½ |
| 60 | 60 mm | 19.1 mm | 9.25 | S½ |
| 61 | 61 mm | 19.4 mm | 9.5 | T |
| 62 | 62 mm | 19.7 mm | 10 | U |
| 63 | 63 mm | 20.1 mm | 10.25 | V |
| 64 | 64 mm | 20.4 mm | 10.75 | V½ |
| 65 | 65 mm | 20.7 mm | 11.25 | W½ |
| 66 | 66 mm | 21.0 mm | 11.5 | X½ |
| 67 | 67 mm | 21.3 mm | 12 | Y |
| 68 | 68 mm | 21.6 mm | 12.25 | Z |
How it is calculated
The French size is the inside circumference of the ring in millimetres: a size 52 ring measures 52 mm around. It is also the European size defined by the ISO 8653 standard.
The US size is derived from the inside diameter with the usual formula diameter = 11.63 + 0.8128 × size. The UK size moves up one letter roughly every 1.2 mm of circumference, starting from A.
Conversions vary slightly from one house to another. Between two sizes, check the seller's guide before ordering.
Good to know
- Measure at the end of the day, when fingers are slightly larger, and avoid doing it in the cold or right after exercise.
- A wide band, over about 6 mm, fits tighter: allow half a size or a full size more.
- If your knuckle is wider than the base of your finger, measure both and pick a size in between, so the ring slides on without spinning.
- For a surprise ring, quietly borrow a ring worn on the same finger and use the "With a ring" method.
Ready to choose
Our selection brings together pieces picked by the editors, from houses whose work we follow.
