I'm afraid that you regard the size as Euro Size and US Size.please do not follow system size chart !!!
if you want make a very correct choice you should choose by the size chart at the Second image !!!

>available: XS， S， M， L， XL

>ASIA SIZE Shoulder/ Chest/ Length/ Sleeve/
XS: 42cm/ 92cm/ 87cm/ 57cm/
S: 44cm/ 98cm/ 89cm/ 59cm/
M: 46cm/ 105cm/ 91cm/ 60cm/
L: 47cm/ 112cm/ 93cm/ 61cm/
XL: 48cm/ 118cm/ 95cm/ 62cm/