“Ideal body weight” formulas were never really about appearance: pharmacists and anaesthetists built them to dose medicine safely. Hamwi (1964) started it, Devine (1974) popularised it, and Robinson and Miller (both 1983) recalibrated it against newer data. Each takes a base weight at 5 feet tall and adds a fixed amount per inch above that — Devine adds 2.3 kg per inch for both sexes (from 50 kg for men, 45.5 kg for women), Robinson 1.9/1.7 kg, Miller 1.41/1.36 kg, Hamwi 2.7/2.2 kg. Because they were built on different populations, their spread — often several kilos — is itself the honest answer: there is no single ideal weight, there is a healthy zone, and the BMI range for your height shows its edges.
A note on health results: every figure this tool gives is an estimate from a standard formula — it is not medical advice and it does not diagnose anything. Bodies vary, and formulas cannot see your health history. Use the result as a starting point, and consult a clinician or registered dietitian for personal health decisions.
How to use it
Pick your sex — each formula uses a different base weight for men and women.
Enter your height — cm, or feet and inches.
Compare the four results — side by side in kg and lbs, with their average.
Set it against the BMI range — the healthy weight band for your height, 18.5 to 24.9.
What you get
All four classic formulas — Devine, Robinson, Miller and Hamwi, computed properly per inch over 5 ft.
Healthy BMI range alongside — so a single number never stands alone.
kg and lbs — every result in both units.
Works under 5 ft too — the per-inch adjustment subtracts below 5 ft, as the formulas intend.
Frequently asked questions
Which ideal weight formula is best?
None is “true” — they were fitted to different groups in different decades, mostly to guide drug dosing. Devine is the most widely used in medicine. The sensible reading is the cluster: if all four land near each other and inside the healthy BMI range, that zone is a reasonable reference — not a personal prescription.
Why do the formulas disagree?
They start from different base weights at 5 ft and add different amounts per inch — Hamwi adds the most per inch (2.7 kg for men), Miller the least (1.41 kg) — so the taller you are, the wider the spread. At 5 ft exactly, they differ only by their base weights.
Is ideal weight the same as healthy weight?
Not exactly. Ideal weight is a formula output; healthy weight is better described by the BMI 18.5–24.9 range for your height, taken together with body fat, fitness, blood markers and how you actually feel. Many healthy people sit outside a formula’s single number.