1 1 Port number = 6 American size, which is widely used in China. There are two kinds of rings, port number and American size. If it is the port number 1 1, the circumference of your finger is 5 1 mm, if it is the American size 165438+. A girl's finger can't be 64.8 mm To measure the circumference of her finger, cut a piece of 3 mm paper, circle the part where she wants to wear the ring, draw it at the junction, and then measure it with a ruler to know what the circumference is. I hope I can help you.