Good question, when I first began taking my measurements I was unsure of where exactly my “waist” was as well. The Waist is where you are your smallest, for most this is just below the ribcage and a little above your belly button. As for the “belly” measurement that I take of myself, I measure around the largest part of my stomach. This one isn’t generally part of the bust-waist-hips measurements, I include the belly measurement specifically to see the progress made in my “pooch”-area since us ladies tend to carry a good portion of fat there :)