In order to achieve consistent measurement on a 3-dimensional piece of gear like a fluffy, down-filled quilt, we measure the flat pieces of fabric that are sewn together. Due to the shaping of our quilts that make them drape around your body efficiently, you should imagine measuring a circumference, but pulling the sections of the quilt taut and adding the measurements together. Also remember that quilts are designed to have a gap between the edges, so the "circle" will be incomplete. That's why we provide "fits similar to" information in the specs. Finally, shoulder width measurements are taken at the widest part of the quilt, not at the collar.