The sock size is determined by the shoe size. A 13-year-old boy usually wears a size M or L. Size M corresponds to women's shoe sizes 6-9 and men's shoe sizes 4.5-8. A size L corresponds to women's shoe sizes 9.5-12 or men's shoe sizes 8.5-12.5. In addition to shoe size, other factors such as body type, foot structure, and gender influence how large a given pair of socks will be when worn. Socks that fit well should be able to stretch a bit when needed, without being so tight that they cause pain or restrict blood flow. Heels may affect the size you need. If you have high heels then you need larger sizes than if you had flats. Also, feet tend to get bigger due to increased muscle mass (especially in the legs) as you age. Feet also get wider as you age. If you have thinning hair, it may be time to start wearing socks. Wearing socks can help add volume to your hair and give it a healthy look. Your hair will also feel better if you stop using products that contain chemicals that dry out your scalp. Socks are a great way to dress up plain white shirts for work or play. You can also use different colors, patterns, or textures to create a unique outfit. Of course, there are many other reasons why people wear socks.