I measure in:
Very tapered fit
Very loose fit
Place tape around neck where collar usually sits. Measure around your bare neck. Take a loose measurement at this point for a comfortable fit -allow room for one index finger between the tape and the neck.
Measure around fullest part of your chest (usually at the nipple). Hold the tape sufficiently easy -allow room for one index finger between the tape and the body. Keeping tape up under armpits, and make sure that it is centered well over shoulder blades in back and over fullest part of the breast in front.
Measure around your body, where your belly is. Hold the tape sufficiently easy -allow room for one index finger between the tape and the body. Thin people should measure at their thinnest point and large people at their widest.
Stand with heels together. Measure around hips at widest point of seats. Hold the tape sufficiently easy - allow room for one index finger between the tape and the body. Make sure your trouser pockets are empty before applying the tape measure.
Measure, at back, from the center of the lower collar seam to length desired. This figure includes the tail length, so be careful to measure all the way down to below the hips. (FIT TIP - The shirttail should be long enough to completely cover your buttocks.)
Shoulder to Shoulder:
Measure your body from the end of one shoulder to the other end of shoulder (place the tape at the end of shoulder bone, where the arms are connected).
Measure sleeve from shoulder seam down to the palm of the hand. (FIT TIP - The sleeve must be long enough to fit well even when the arm is bent, and not just when the hand is hanging down vertically. Otherwise the cuff recedes far behind the wrist if you bend or lift your arm.)
Measure around the fullest part of the wrist. Hold the tape sufficiently easy -allow room for one index finger between the tape and the body. Take the measure around your bare wrist, not over your shirt.
Open and turn up shirt collar. Place tape around collar band and measure from center of collar button to far end of buttonhole. (FIT TIP -Another way is to use a shirt with a well-fitting collar. Lay the collar out flat and measure from center of collar button to far end of buttonhole).
Width of Shirt Shoulder:
With your shirt on, measure from the back at the end of one shoulder seam to the end of the other shoulder seam.
Your biceps circumference where it is as widest. Hold one finger between the tape and your arm.