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:
>(PANTS SIZE) Waist / Hip / Thigh Width/ Leg Opening/ Length
28: 70cm/ 98cm/ 54cm/ 42/ 100
29: 73.3cm/ 100cm/ 56cm/ 43/ 102
30: 76.7cm/ 105cm/ 57cm/ 43/ 105
31: 80cm/ 108cm/ 58cm/ 44/ 106
32: 83.3cm/ 110cm/ 59cm/ 46/ 109
33: 86.7cm/ 112cm/ 60cm/ 49/ 110
34: 90cm/ 114cm/ 61cm/ 49/ 110
36: 93.3cm/ 116cm/ 62cm/ 49/ 111
38: 96.7cm/ 118cm/ 64cm/ 50/ 112
40: 100cm/ 120cm/ 65cm/ 50/ 113
42: 103.3cm/ 122cm/ 66cm/ 51/ 114