Leggings

bust - Start by placing a measuring tape around the largest part of your bust. The tape should be flat but not too snug.
waist - Your natural waist lies between your bottom ribs and hip bones. To measure, breathe deeply, relax your stomach and lie the tape measure flat around your waist, allowing for a ¼ inch of slack.2
hip - To achieve the most accurate hip measurement, find the widest point of your hips and place the measuring tape around. The hip bone often isn't the widest point - it's one to two inches lower, where your butt is at its fullest.
inseam Friends are helpful for this one. Stand with your feet about shoulder-width apart in running shoes. Measure from the very top of your inner leg to the bottom of your inner ankle; repeat this process on your left leg and average out to achieve your most accurate inseam length.