Most people's middle finger is the second thickest finger after the thumb. The average middle finger ring circumference for women is size 12-15, and the inner circumference is 52.4-55.5mm.

Because of its longest length, it is suitable even for thick and heavy ring designs. It is also recommended to wear a V-shaped ring on the middle finger to make the finger appear more slender and well-proportioned.

A simple way to measure your ring circumference yourself
Wrap a piece of paper about 3mm wide around the finger you want to measure. After connecting the ends of the paper, measure the length of the paper to get the circumference of the finger. The number closest to the circumference of this circle is your ring size.

When using this measurement method, you want to make sure that the strip of paper is wrapped around the thickest part of your finger, which typically would be the finger joints: the first knuckle of the thumb, and the second knuckle of the other fingers. It shouldn't be too tight or too loose. You can think of applying it as evenly as you can with a Band-Aid so that you get the closest number to the actual size.

The paper strip is shaped like a ring, but if you're measuring your own finger, it might be easier to wrap it around your finger with clear tape and mark it with a grease pen.

After we actually tried it, the tester’s actual ring circumference was size 7, but the paper strip measured it to be size 11, and the tape measured it to be size 10. Because fingers, paper, and tape all move, and especially paper and tape slide easily, there may still be errors in measurement, so this number can only be used as a reference. In particular, as long as the ring size differs by 1mm in inner diameter, it will be one size different, which will also affect the wearing. Therefore, it is recommended to actually wear the ring and measure it to get the accurate number.