Measure around the narrowest part of the natural waistline. To find your natural waistline, bend to one side. There will usually be a crease where you bend. Often it is just below your ribcage. That's your natural waistline. Don't worry since this may seem higher than where you actually wear your pants and jeans. But this is the point that is so important for a great fit. Try to keep the tape measure parallel to the floor as you measure all the way around your torso. That's your natural Waist Circumference.