Chest: Measure under your arms, across the widest part of your chest.
Waist: Measure your natural waistline

Casual tops
Size Small Medium Large X-Large XX-Large
To fit chest 36" 38" 40" 42" 44"
Casual bottoms
Size Small Medium Large X-Large XX-Large
To fit waist 30" 32" 34" 36" 38"