Small = 34" - 36" (Half Chest = 48cm)
Medium = 38" - 40" (Half Chest = 52cm)
Large = 42" - 44" (Half Chest = 56cm)
XLarge 46" - 48" (Half Chest = 60cm)
XXLarge = 50" - 52" (Half Chest = 65cm)
NOTE: 1/2 chest measurements = this is the flat width of the clothing and is used to allow you to get a direct comparison to other clothing you own.
Lay a well fitting hoodie / t-shirt flat on a surface and measure straight across the front of the garment from armpit to armpit.