Sizing men’s dress shirts isn’t as simple as it might seem. Some brands like to try to ease consumers' minds by supplying shirts in sizes like medium, large and so on; but these types of sizings only serve to complicate matters. Men’s dress shirts are sized according to a man’s measurements: the neck, arm, and chest measurements determine the size of the dress shirt. If you know your measurements, you can measure the dress shirt with a tape measure and know for a fact if the shirt will fit.
Measure around the center of your neck with the tape measure. Don’t tightly wrap the tape measure around your neck. Put two fingers under the tape measure to simulate the room between your neck and a collar. Write down this neck measurement with the pencil on the notepad.
Wrap the tape measure around your chest, under your arms and across your back. Don’t wrap the tape measure snugly. You want to be able to breathe and move without restriction. Add one inch to the measurement and write this measurement on the notepad with the pencil. This is your chest measurement.
Place the tape measure at the base of your neck where the back of the neck connects with your shoulder. Place the first inch of the tape measure there and hold it with your left hand reaching behind your neck. Allow the tape measure to trail over the right shoulder, along your right upper arm to your right elbow, and then down into your right hand. Grasp the tape measure with your hand and tug out any slack. Note the measurement that hits your wrist. This is your arm measurement. Write this measurement on the notepad with the pencil.
Use your neck measurement to determine the collar or neck size of the shirt you need. Use the chest measurement to determine the shirt’s chest allowances. Use the arm measurement to determine the arm length of the dress shirt.
Men’s dress shirts traditionally are available in all sizes, even half sizes. If you are in doubt, get the next half size up from your measurement. You can always camouflage a slightly too big collar with a tie, but you can’t comfortably button a collar that’s too tight. Some department stores allow you to special order very short or very long arm lengths and don’t regularly stock them. If you have very short or long arms and need an arm length not on the shelves, ask a store clerk for ordering instructions.
Many brands are now offering different “cuts” in their dress shirts. A cut is the way the shirt was cut and sewn. Athletic cut allows for wider shoulders but a tapered waist to accentuate an athletic physique. "Regular" cuts aren’t as tapered as the "Athletic" cut. Most shirts, unless otherwise marked, are regular cut. Some brands offer a "Full" cut. This means the torso section of the shirt is loose and extra fabric has been allowed. The shirt tail will be slightly longer in to allow more fabric to tuck in.