Find your fit, measure your waist:
XS - 30 in (76 cm)
S- 32 in (82 cm)
M - 34 in (88 cm)
L - 37 in (94 cm)
XL - 39 in (100 cm)
XXL - 42 in (106 cm)
Stick with your usual size — Sabbes fit just like other leading underwear brands (Calvin Klein, Nike, Björn Borg, etc).