To choose the correct size for you, measure your body as follows
Measure the space between your shoulder points. Position the end of the tape flat against your back at the first shoulder point. You should be measuring across the broadest part of your shoulders which usually land out roughly to 1 to 2 inches (2.5cm to 5cm) below the neckline.
Measure under arms around the fullest parts of your bust. Be sure to keep tape level across back and comfortably loose.
Measure around natural waistline or the smallest part of your space a measuring tape.
Measure the circumference of your hips. Start at one hip and wrap the tape measure around your rear, around the other hip, and back to where you started. Make sure the tape is over the largest part of your hips.
Start from the top of your shoulders and measure vertically till your desired length.