Size Reference Guide
US Size and Inner Circumference (mm) Conversion Chart
The following chart displays the detailed correspondence between US sizes and inner circumference (in millimeters) in a 4-column layout, making it easy for you to select the appropriate size according to your needs. You can quickly find specific size information using the search box above.
US Size / Circumference
2
41.7 mm
3
42.9 mm
3.5
45.5 mm
4
46.8 mm
4.5
48.0 mm
US Size / Circumference
5
49.3 mm
5.5
50.6 mm
6
51.9 mm
6.5
53.1 mm
7
54.4 mm
US Size / Circumference
7.5
55.7 mm
8
57.0 mm
8.5
58.3 mm
9
59.5 mm
9.5
60.8 mm
US Size / Circumference
10
62.1 mm
10.5
63.4 mm
11
64.6 mm
12
67.2 mm
12.5
68.5 mm
Size Explanation
The inner circumference sizes in the table are standard measurements. Actual products may vary slightly by style.
Measurement Tips
When measuring, maintain a natural state and avoid being too tight or too loose for the most accurate size.
Help Center
If you have questions about size selection, contact customer service for professional advice. We're here to help.