To measure yourself, place a tape measure under your arms and measure all the way around your body. If your measurement is close to a size, you may wish to consider going up to the next sized garment.
Ladies Sizing: XS - 8, S - 10, M - 12, L - 14, XL - 16, 2XL - 18
Men's Sizing: XS - 34", S - 36", M - 40", L - 44", XL - 48", 2XL* - 52", 3XL* - 56", 4XL - 60", 5XL - 64"