The most important consideration when measuring for a business shirt is comfort. The garment should be full enough so you can move comfortably without it pulling, and yet sits under a suit or jacket without spoiling he silhouette.
The cuff should show approximately half an inch (1.25cm) beneath the sleeve of the jacket. The cuff itself should fit snugly enough to hold its place on the wrist without appearing tight.
A shirt that fits properly should have a neckband with enough room so that you can fit two fingers in when buttoned, and yet not too loose that it gathers when worn with a tie.
Measure around the fullest part of your neck. Ensure the tape measure is level all the way round and take the measurement with two fingers underneath the tape. This will ensure your collar is a comfortable fit, and yet not too tight.
Measure the widest part of your chest, with the tape measure tucked just under your armpits. Please make sure the tape is level, and horizontal to the floor.
Men's Sleeve Length
Measure from the centre back of your neck, across your shoulder, and then down to your wrist bone, or to where you would like your cuff to sit. It may help if you place your hand on your hips to allow for ease. Round up to the nearest available sleeve length.
Measure from your shoulder blades around to the fullest part of your bust
Measure around at the narrowest point of your waist.