Ask “what’s my ideal weight?” and you’ll get a different number depending on which decades-old medical formula you look up. That’s not a bug in any one of them — it’s because each was derived by a different group of researchers, at a different time, from different reference populations. Our Ideal Weight Calculator sidesteps picking a “winner” by showing all four at once.
The four formulas
- Devine (1974) — originally created for drug dosing calculations, still the most widely used today in clinical contexts.
- Robinson (1983) — a refinement using a different reference dataset.
- Miller (1983) — published the same year as Robinson, with its own slightly different coefficients.
- Hamwi (1964) — the oldest of the four, still commonly cited in nutrition and dietetics.
All four take the same two inputs — height and sex — and apply a simple linear formula: a base weight for being exactly 5 feet tall, plus a fixed amount added per inch over that.
A worked example
For a 175 cm (about 5’9“) male: Devine gives 70.5 kg, Robinson gives 68.9 kg, Miller gives 68.7 kg, and Hamwi gives 72.0 kg — a spread of about 3.3 kg (7 lb) across all four. That spread itself is useful information: it tells you these are rough historical reference points clustering in a range, not a single precise target.
What these formulas don’t account for
None of the four factor in frame size, muscle mass, or body composition — they’re purely height- and sex-based. That means a heavily muscled athlete and a smaller-framed person of the same height and sex get the exact same “ideal weight” number, even though their healthy body compositions could look very different. These formulas originated largely to solve a specific clinical problem (standardizing drug doses independent of a patient’s actual, possibly unusual, body weight), not to set personal fitness goals.
Should you use this for a weight-loss goal?
Treat it as a reference point, not a target. A healthcare provider factoring in your actual body composition, health markers, and history will give far more useful guidance than any one of these four decades-old formulas on its own.
Try it yourself: Ideal Weight Calculator.