What "ideal weight" really means
Ideal body weight (IBW) formulas were created for clinical use — most famously, the Devine formula was developed for calculating medication doses — not as beauty standards. Each estimates a reference weight from just your height and sex, which is also why they disagree with each other: real bodies differ in muscle, bone structure, and frame size in ways two variables can't capture.
The four formulas
All four use the same pattern: a base weight at 5 feet tall, plus an increment for every inch above it. Devine adds 2.3 kg per inch for both sexes; Robinson, Miller, and Hamwi use slightly different bases and increments derived from different datasets. The spread between the four results — usually a few kilograms — is itself the most honest answer: ideal weight is a range, not a point.
How to use your result
Treat the range as a rough reference, not a target to chase to the decimal. A muscular person can be perfectly healthy above it; a small-framed person may sit naturally below it. For a fuller picture, check your BMI, estimate your body fat percentage, and — most importantly — judge progress by strength, energy, blood work, and how you feel. If you do want to move toward the range, our calorie calculator can set a sensible daily target.
Sources & references
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.
- Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Ann Pharmacother. 2000;34(9):1066–1069.