1020 thigh oversized
grasp the thighs on both sides (+/- 10 cm under the crotch) and give the oversize you want between your fingers. (give the double folded distance from 1 side) keep symmetry in mind (the same amount on both sides).
If you want comfort, choose 2cm here, if you want them tighter than 1cm. If you want wide pants, go plus 2cm.