The underbust is the area located below the bust (or pectorals on those without a bust). We use the vertical length from right below the bust to the waist, to determine if you're long or short-waisted. Some corsets will be patterned for a long or average underbust length. Other corsets will fit all body types vertically (without being too long) but can be on the shorter end. If you're concerned with a corset being too long or too short (leading to a bit of fluff below the bust if the corset is truly centered on the waist). Please remember to take this measurement, and compare it to our sizing diagrams for each corset you may be interested in.