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.
Practical guide for using this result
Why several formulas are shown
Devine, Robinson, Miller and Hamwi use different constants. Their spread illustrates the uncertainty rather than identifying a single correct weight.
How to choose a personal target
Combine the formula range with current waist, blood pressure, laboratory markers, movement and a weight you can maintain with normal habits.
When maintenance is the better goal
If health markers and function are good, maintaining a stable weight may be more appropriate than pursuing a lower formula value.
How to interpret an “ideal weight” range
Formula results are historical reference estimates, not a personalised medical target. Body frame, muscle, age, ethnicity and health goals can make a different stable weight appropriate.
Use the overlap, not one formula
When several formulas cluster, the overlap is a rough reference. A disagreement between formulas shows why the result should be treated as a range.
Compare with current health markers
Waist size, strength, menstrual health, blood pressure, laboratory results and quality of life add context that a height-based formula cannot provide.
Avoid rapid pursuit of the number
If weight change is appropriate, use a gradual plan that preserves protein, micronutrients, sleep and training performance. A clinician can help when there is illness or eating-disorder risk.
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.