A link to the size chart for individual garments can be found immediately below the 'Size' options on each product page:

 

An image showing where the size chart link can be found on a product page

UK sizes are shown by default, some common equivalent international sizes are shown in the tables below:

 

Men's tops
 UK EU Japan
34 44 0
36-38 46-48 1
38-40 48-50 2
40-42 50-52 3
42-44 52-54 4
44-46 54-56 5
46-48 56-58 6

 

Women's tops
 UK EU US Japan Australia
4 32 2 5 6
6 34 4 7 8
8 36 6 9 10
10 38 8 11 12
12 40 10 13 14
14 42 12 15 16
16 44 14 17 18
18 46 16 19 20
20 48 18 21 22