How do you convert American shoe sizes in to English sizes?

you can generally convert European sizes to American with these rules

suits and sportjackets: subtract 10 so a 50 euro is a 40 US

slacks: subtract 16 so a 48 euro is a 32 US

dress shirts: 38 = 15, 39 = 15.5, 41 = 16, 42 = 16.5, 43-17, 44 = 17.5, 46 = 18

knit shirts: 48 = M, 50 = L, 52 = XL, 54 = XXL