Wrap a measuring tape around your neck (flush to the skin) at the height where the collar would be if you were wearing a shirt. Enter the exact length.
Stand up naturally with hands down at your side. Put tape around the fullest part of the chest. Tape should be snug with one finger between tape and body.
You must (and I’ll repeat) you must actually measure your skin waist or the finished waist from your best fitting slacks to get the real waist measurement you are comfortable with.
Measure the Outseam of your best fitting slack’s – This is the outer seam of the slacks measured from the top of waistband to the bottom.