Size guide.

Men's sizes

Size	Jeans	Waist
XS	28	26-28 inch
S	29	28-30 inch
M	30/31	30-32 inch
L	32/33	32-34 inch
XL	34/36	34-36 inch
XXL	38/40	36-38 inch
3XL	42	38-40 inch

Boy's sizes

Size	Age
104	3-4
110-116	5-6
122-128	7-8
134-140	9-10
146-152	11-12