To choose the correct size for you, measure your body as follows:

• Chest :
  Measure around the fullest part, place the tape close under the arms and make sure the tape is flat across the back.
• Here are some measurements for men's tops:
  XS: Body length: 29 in, chest: 39 in, sleeve length: 34 in
  S: Body length: 29 in, chest: 40 in, sleeve length: 34.5 in
  M: Body length: 29.5 in, chest: 42 in
  L: Body length: 30 in, chest: 46 in
  XL: Body length: 30.5 in, chest: 50 in
  XXL: Body length: 30.5 in, chest: 54 in