To convert cm to ring size, measure the inside circumference of your finger or ring in centimetres and match it to the chart below. A 5.2 cm circumference is US size 6, 6.0 cm is US size 9 and 7.0 cm is US size 13. If you have a diameter instead, multiply by 3.1416 first.
Ring Size Chart in CM (4.5 to 7.0 cm)
Circumference is the distance around the inside of the ring. US sizes are rounded to the nearest half size, with the exact value shown so you can see how close you are.
| Circumference (cm) | Inner diameter (cm) | Exact US size | Nearest US size | UK size | EU size |
|---|---|---|---|---|---|
| 4.5 | 1.43 | 3.31 | 3.5 | G | 45 |
| 4.6 | 1.46 | 3.71 | 3.5 | G | 46 |
| 4.7 | 1.50 | 4.10 | 4 | H | 47 |
| 4.8 | 1.53 | 4.49 | 4.5 | I | 48 |
| 4.9 | 1.56 | 4.88 | 5 | J½ | 49 |
| 5.0 | 1.59 | 5.27 | 5.5 | K½ | 50 |
| 5.1 | 1.62 | 5.66 | 5.5 | K½ | 51 |
| 5.2 | 1.66 | 6.06 | 6 | L½ | 52 |
| 5.3 | 1.69 | 6.45 | 6.5 | M½ | 53 |
| 5.4 | 1.72 | 6.84 | 7 | N½ | 54 |
| 5.5 | 1.75 | 7.23 | 7 | N½ | 55 |
| 5.6 | 1.78 | 7.62 | 7.5 | O½ | 56 |
| 5.7 | 1.81 | 8.01 | 8 | P½ | 57 |
| 5.8 | 1.85 | 8.41 | 8.5 | Q½ | 58 |
| 5.9 | 1.88 | 8.80 | 9 | R½ | 59 |
| 6.0 | 1.91 | 9.19 | 9 | R½ | 60 |
| 6.1 | 1.94 | 9.58 | 9.5 | S½ | 61 |
| 6.2 | 1.97 | 9.97 | 10 | T½ | 62 |
| 6.3 | 2.01 | 10.36 | 10.5 | U½ | 63 |
| 6.4 | 2.04 | 10.76 | 11 | V½ | 64 |
| 6.5 | 2.07 | 11.15 | 11 | V½ | 65 |
| 6.6 | 2.10 | 11.54 | 11.5 | W½ | 66 |
| 6.7 | 2.13 | 11.93 | 12 | X½ | 67 |
| 6.8 | 2.16 | 12.32 | 12.5 | Z | 68 |
| 6.9 | 2.20 | 12.71 | 12.5 | Z | 69 |
| 7.0 | 2.23 | 13.10 | 13 | Z½ | 70 |
Match your number to the closest row. EU size equals the circumference in millimetres, which matches ISO 8653:2016 as described on Wikipedia. For the full US, UK and EU lists, see the ring size conversion chart.
Quick Lookup: Common CM Measurements
| Circumference (cm) | Exact US size | Nearest US size | UK size | EU size |
|---|---|---|---|---|
| 5.0 | 5.27 | 5.5 | K½ | 50 |
| 5.2 | 6.06 | 6 | L½ | 52 |
| 5.4 | 6.84 | 7 | N½ | 54 |
| 5.6 | 7.62 | 7.5 | O½ | 56 |
| 5.8 | 8.41 | 8.5 | Q½ | 58 |
| 6.0 | 9.19 | 9 | R½ | 60 |
| 6.2 | 9.97 | 10 | T½ | 62 |
| 6.4 | 10.76 | 11 | V½ | 64 |
| 6.6 | 11.54 | 11.5 | W½ | 66 |
| 7.0 | 13.10 | 13 | Z½ | 70 |
How to Measure Ring Size in CM
- Cut a strip of paper about 1 cm wide and 15 cm long.
- Wrap it around the base of your finger so it is snug but can slide over the knuckle.
- Mark where the end overlaps the strip.
- Lay the strip flat and measure from the end to the mark with a ruler in centimetres.
- Find that number in the chart above.
Measure three times on different days, with warm hands. For a full method, read how to measure your ring size, or print a sizer from the printable ring size chart.
CM, Inches and Millimetres
1 cm equals 10 mm and 0.3937 inches. Use the inches to ring size chart for inch measurements and the mm to ring size chart for millimetres. Our US ring size chart and UK ring size chart list each size with its measurements.
Frequently Asked Questions
What ring size is 7 cm?
A 7 cm inner circumference is 70 mm, which is about US size 13, UK Z½ and EU 70. For a cm figure of 6.5, see our guide on what is a 6.5 cm ring size.
What ring size is 6.5 cm?
A 6.5 cm circumference is 65 mm, which falls at US 11 (exact 11.15), UK V½ and EU 65.
What size ring is 6 cm?
6.0 cm is 60 mm around, which is about US 9, UK R½ and EU 60.
Is the cm measurement the diameter or the circumference?
On this page, cm means the inner circumference, the distance around the inside of the ring. If your number is a diameter, multiply it by 3.1416 to get the circumference. For example, 1.7 cm across is 5.34 cm around, about US 6.5. For diameters in mm, use the mm to ring size chart.
How do I convert cm to inches for ring size?
Divide centimetres by 2.54. A 5.2 cm circumference is 2.05 inches. The inches to ring size chart covers inch measurements.
Should I round up or down if my cm result is between sizes?
Check the exact US size column. If you are between two half sizes, size up for wide bands and down for narrow ones. See finding the perfect fit in between ring sizes.