The four formulas were developed for medical purposes — drug dosing, ventilator settings, surgical risk. Each gives a slightly different number because they were calibrated to different populations.

For everyday body-composition goals, the healthy BMI range (18.5–24.9) is usually the most useful answer. The formulas give you a single point inside (or near) that range.

Body composition matters more than scale weight. Pair this with the Body Fat Calculator to set a sensible target.