Finding the right size for a dress shirt can be a little difficult.In US and Britain, Dress shirts have two different measurements, your neck size and your sleeve length, both in inches.See how to take the measurements here.
When you have your neck measurement, round it up to the nearest whole or half size. For example, if your neck measures 16.3, choose a 16.5 collar.
Add an extra inch to your sleeve measurement, and round this up to the nearest even number.
There are also different fits, Slim, Athletic, Regular and Full. Slim is tight around the chest and sides. The athletic fit (also called tailored fit) is tighter at the waist, but leaves more room for the chest. The regular is the standard fit and quite loose, and the full size the loosest.
·Check the cuff size. When you button the cuff, it shouldn't be able to slip over your wrist.
·Make sure the shirt fits properly over your shoulders. The shoulder seam should be right where your shoulder ends.
·Tuck the shirt and stretch your arms over your head. The shirt should be long enough not to get untucked.
·Bend your arm. The shirt sleeve should be long enough so that the cuff doesn't slide up your forearm.