Before you start measuring... remember, size is just a number. Don't suck in or pull the tape measure tight. Stand in a relaxed position, let it all hang out and measure with a taught, but not tight tape measure. It's better to get the RIGHT size than worry about what the size is.
WAIST: Measure the narrowest point on your torso, around your waist.
HIPS: Measure around the widest part of your hips.
CHEST: Measure the largest part of your chest. Usually this is where your nipples are.
Measurements are in inches
XS
S
M
L
XL
XXL
Width
15 ½
17 ½
19 ½
21 ½
23 ½
25 ½
Length
28
29
30
31
32
33