Use a measuring tape and pull it firm, but not tight. 

• Sleeves
  Measure from the center of the back below the collar over the shoulder and down to the wrist.

   

• Neck
  Measure below the Adam's apple.

   

• Waist
  Measure over the shirt, but not over pants or belt at the desired position usually around the navel.

   

• Inseam
  Lay a pair of pants on a flat surface.  Measure on the outside of the leg from the top of the waistband to the bottom.  This gives you an outseam measurement.  Now subtract 10 inches from that figure (10.5 inches for waist size 36 and larger) to get the inseam measurement. For example, if the outseam is 38 inches you should order a 27.5 inch  inseam.

   

• Chest
  Measure at the broadest point with the tape under the armpit.