Ring Size Converter → CM to Ring Size Converter
CM to Ring Size Converter
Measured around your finger in centimeters? Enter it below to get your ring size in every standard. Most adult sizes fall between 4.4 cm and 7.0 cm around.
Your US size—
Enter a measurement above to see your size in every standard.
CM to Ring Size chart
| Circumference (cm) | Diameter (mm) | US / CA | UK / AU | Europe |
|---|---|---|---|---|
| 4.42 | 14.1 | 3 | F | 44 |
| 4.55 | 14.5 | 3.5 | G | 45½ |
| 4.68 | 14.9 | 4 | H½ | 47 |
| 4.80 | 15.3 | 4.5 | I½ | 48 |
| 4.93 | 15.7 | 5 | J½ | 49 |
| 5.06 | 16.1 | 5.5 | K½ | 50½ |
| 5.19 | 16.5 | 6 | L½ | 52 |
| 5.31 | 16.9 | 6.5 | M½ | 53 |
| 5.44 | 17.3 | 7 | N½ | 54 |
| 5.57 | 17.7 | 7.5 | O½ | 55½ |
| 5.70 | 18.1 | 8 | P½ | 57 |
| 5.83 | 18.5 | 8.5 | Q½ | 58 |
| 5.95 | 19.0 | 9 | R½ | 59½ |
| 6.08 | 19.4 | 9.5 | S½ | 61 |
| 6.21 | 19.8 | 10 | T½ | 62 |
| 6.35 | 20.2 | 10.5 | U½ | 63½ |
| 6.46 | 20.6 | 11 | V½ | 65 |
| 6.59 | 21.0 | 11.5 | W½ | 66 |
| 6.72 | 21.4 | 12 | Y | 67½ |
| 6.84 | 21.8 | 12.5 | Z | 68½ |
| 6.97 | 22.2 | 13 | Z+1 | 70 |
Industry-standard approximations; manufacturers vary slightly. If you're between sizes, round up.
FAQ
What ring size is 5.4 cm?
A finger circumference of 5.4 cm (54 mm) is about a US size 7 (UK N½, EU 54). Enter your exact measurement above for the precise match.
How do I measure my ring size in cm?
Wrap a strip of paper or string around the base of your finger, mark the overlap, and measure the length in centimeters. That circumference maps directly to a ring size — European sizes are literally that number in millimeters.