Ideal Body Weight: What the Formulas Actually Say
The concept of an "ideal" body weight is older than you might think — these formulas were originally designed for drug dosing in clinical medicine, not for fitness goals. Understanding where they come from helps you use them without putting too much weight on any single number.
The major formulas compared
The most commonly used formulas — Hamwi, Devine, Robinson, and Miller — all take height as their primary input and return a baseline weight, with adjustments for sex. They typically agree within 2–4 kg of each other. Our calculator shows the range across all four so you see a realistic band rather than a single point.
What the formulas miss
These formulas ignore age, muscle mass, bone density, and ethnic differences in body composition — all of which are clinically meaningful. A 60-year-old woman and a 25-year-old competitive swimmer of the same height will have very different "ideal" weights in practice.
How to use this number
Use the ideal weight range as a ballpark, not a target. Pair it with your BMI and, if possible, a body fat percentage measurement. If your weight is inside the range and you feel healthy, the number is reassuring. If you are outside it, speak with a clinician before setting a weight goal.