Men's Shirt

Width of Shoulder
With your T-shirt on, measure from the back at the end of one shoulder seam to the end of the other shoulder seam.
Cross Shoulder
Measure across the back of your coat between the 2 junctions of the sleeve and armholes.

Cross Chest
Measure your front chest. Measure to the nearest inch.
Measure around your chest up underneath your armpits and across its maximum point. Measure yourself in a shirt and make sure the tape goes up over your shoulder blades at the back. Measure to the nearest inch.

The jacket waist is measured an inch or two higher up than for your pants waistband, around the height of your belly button. Large gentlemen should measure their jacket waist at the widest point, and slim gentlemen at their narrowest. Measure to the nearest 1/2 inch.
Measure around the fullest part of your waist.

Measure around your hips and buttocks at their widest point. Measure to the nearest 1/2 inch.
Jacket Length
This figure includes the tail length so be careful to measure from the lower back collar band seam all the way down to below the hips.

Neck Size
Wrap the tape around the neck just below the adam's apple. Allow room for one index finger between the tape and the neck. Another method is to use a shirt with a well-fitting collar. Simply, lay the collar out flat and measure from center of collar button to far end of button hole.

Sleeve Length
Measure each arm from the top of the shoulder seam down to just below the wrist bone. Arm lengths can differ slightly, so if the right arm measurement isn't the same as the left don't be surprised. To double check your accuracy, measure from the tip of each thumb, up 4 1/2" toward the wrist bone. Make a mark at this point. Now measure from the shoulder seam down to the mark. This technique will reveal the difference in arm lengths.