Measure your neck from the bottom end and make sure you leave a margin of two fingers between your neck and the measuring tape. This will make your collars fit you perfectly and leave some room for comfortable movement.
Sleeves should be measured from top of the shoulder till the wrist, where you will be fastening your cuffs. Make sure you are standing straight with your arms hanging straight on your sides.
Measure chest from the broadest part of your chest while holding the breath inside. Leave some room for comfort (two to three ﬁngers depending on your preference)
Measure around your natural waistline, which is the narrowest part of your waist. You can choose the ﬁt or suggest how lose you want the shirt to be around your waist.
Measure your shoulders from behind your neck. Take measurement from the top-center of one shoulder to the top-center of the other.
Measure your front length from the HPS (Highest point on shoulder), which is just where your collar starts, to where you want the shirt to fall on you. Go for a slightly longer length for a straight hem formal shirt, to keep it tucked in your trouser better.