About this calculator
"Ideal weight" formulas were never really about appearance. They were clinical tools — Devine's equation, the most widely used, was developed for calculating drug dosages and later adopted for nutrition and ventilator settings. Each formula starts from a base weight at 5 feet tall and adds a fixed amount per inch above that, which is why they agree closely for average heights and drift apart at the extremes.
Modern medicine leans on ranges rather than a single "ideal" number: the healthy BMI span (18.5–24.9) is shown alongside the formulas for comparison. Frame size, muscle mass and age legitimately move a healthy target within — and sometimes outside — any of these outputs, so use them as a map, not a verdict.
How to use it
- Select your sex and units.
- Enter your height (total inches, e.g. 70 for 5 ft 10 in, or centimeters).
- Compare the four formulas — their spread is the honest answer — against the healthy BMI range.
The formula
All four share the same skeleton — a base weight at five feet plus a per-inch increment — and differ in calibration data. Devine is the medical standard; Hamwi came from diabetes nutrition practice; Robinson and Miller refit the same idea to newer population data in 1983.
Worked example
For a man of 5 ft 10 in (70 in): Devine gives 73.0 kg (160.9 lb), Hamwi 75.0 kg, Robinson 71.0 kg, Miller 70.3 kg — a spread of about 10 lb. The healthy BMI range for that height is wider still: 58.5–78.7 kg (129–174 lb). For a woman of 5 ft 5 in, Devine suggests 57.0 kg (125.7 lb).
Frequently asked questions
Which ideal weight formula should I trust?
None of them individually — they were calibrated on limited populations decades ago. The practical approach: take the cluster of the four formulas as a center estimate, and the healthy BMI range as outer bounds. If your weight sits in the overlap and your waist, fitness and lab markers are good, the formulas have nothing to add.
Do these formulas account for frame size or muscle?
The original Hamwi method suggested adjusting ±10% for large or small frames, judged by wrist circumference relative to height. None of the formulas accounts for muscle mass: lean athletes routinely sit above their "ideal" weight in excellent health, which is one reason medicine moved toward ranges and waist measures.
Why does medicine still use the Devine formula?
Because many drug dosages (especially for kidneys-cleared medicines) and clinical nutrition calculations were validated against "ideal body weight" as Devine defined it. It persists as a dosing input even though doctors rarely present it to patients as a weight goal anymore.
What weight should I actually aim for?
A reasonable target for most people is anywhere inside the healthy BMI range that they can maintain comfortably with good habits — ideally toward the part of the range where their waist circumference, blood pressure and blood markers look best. Losing 5%–10% of body weight, even without reaching any formula's number, produces most of the measurable health gains.