Ring size calculator
Enter the circumference or diameter of your finger to find your ring size.
Ring size is measured by the finger circumference in millimetres. In France and most European countries, the size equals this circumference: size 52 = 52 mm around the finger. Inner diameter (in mm) is also sometimes used.
Fingers swell with heat and during the day. Measure in the evening, on the finger that will actually wear the ring. For a wedding band, measure the ring finger of the right hand. If your knuckles are prominent, add 1 mm so the ring can slide over.
- Cut a strip of soft paper about 1 cm wide.
- Wrap it around your finger, snug but not tight.
- Mark precisely where the strip overlaps.
- Measure the length up to the mark: that is your size in mm.
Full table
| FR size | Diameter (mm) | Circumference (mm) | US size | UK size | DE size |
|---|---|---|---|---|---|
| 44 | 14 | 44 | 2¾ | E½ | 44 |
| 46 | 14.6 | 46 | 4 | H½ | 46 |
| 48 | 15.3 | 48 | 4¾ | I½ | 48 |
| 50 | 15.9 | 50 | 5½ | K | 50 |
| 52 | 16.6 | 52 | 6¼ | L½ | 52 |
| 54 | 17.2 | 54 | 7 | N | 54 |
| 56 | 17.8 | 56 | 7¾ | O½ | 56 |
| 58 | 18.5 | 58 | 8½ | Q | 58 |
| 60 | 19.1 | 60 | 9¼ | R½ | 60 |
| 62 | 19.7 | 62 | 10 | T | 62 |
| 64 | 20.4 | 64 | 10¾ | U½ | 64 |
| 66 | 21 | 66 | 11½ | W | 66 |
| 68 | 21.6 | 68 | 12¼ | Y | 68 |
Frequently asked questions
What's the difference between diameter and circumference?
Circumference is the loop around the finger in mm (= FR size). Diameter is the internal width of the ring in mm. Diameter = circumference / pi. A size 52 has an internal diameter of about 16.6 mm.
Should I leave any margin?
For an everyday ring, take your exact size. If measuring in the morning or in cold weather, add 0.5 to 1 mm. If your knuckles are prominent, add 1 mm so the ring slides over the joint.
Why are US sizes so different?
US sizes follow their own scale, not based on mm circumference. US size 6 = 16.5 mm diameter = FR size 52. Our table covers all FR / US / UK / DE / Italy correspondences.
How can I tell an existing ring's size?
Measure its internal diameter with calipers, or its internal loop with a thread. Convert to mm to get the FR size. Any jeweller can do it for free with a ring sizer.