What is ideal body weight?
Ideal body weight (IBW) is a single estimate of a reasonable weight for your height and sex, calculated from one of several formulas doctors have used since the 1960s. It was originally built for a practical job, not a fitness goal: working out drug doses (many medicines are dosed by weight) and estimating calorie and protein needs for patients who could not be weighed reliably.
Because each formula was published by a different researcher at a different time, no two give exactly the same number. This calculator shows all four side by side, plus the healthy BMI range for your height, rather than picking one as "correct".
How it is calculated
All four share the same shape — a base weight at 5 feet, plus a fixed amount per inch above that — because they were fitted to similar clinical data decades apart. Devine is the one most widely cited in medical dosing guidance today; Hamwi was originally developed for planning diabetic diets; Robinson and Miller are later refinements of the same idea.
Worked example
Man, 5 ft 9 in (175 cm)
- Robinson
- 69.1 kg
- Miller
- 68.9 kg
- Devine
- 70.7 kg
- Hamwi
- 72.3 kg
- Average of the four
- 70.2 kg
A roughly 6 kg spread across four formulas is normal — none of them is more "right" than the others.
Ideal weight vs healthy weight — and why they can disagree
Ideal body weight is one number from a height-and-sex formula with no concept of a range. Healthy weight (see the Healthy Weight Calculator) is a range — 18.5 to 22.9 BMI on the Asian cut-offs for Indians, wider at 18.5 to 24.9 on the WHO scale — and is generally the more clinically useful figure today.
- None of the four formulas use age, frame size or muscle mass, so a naturally broad-framed or very muscular person can be well above every formula's number and still be healthy.
- They were built from mostly Western adult data; no India-specific version exists, which is one reason the Asian BMI range is often the better reference for Indians.
- Treat the four results as a plausible band, not a single target to hit exactly.
Ideal body weight is a general reference figure, not a personal target set by a doctor. It does not account for your build, muscle mass, medical history or goals — talk to a doctor or dietitian before using it to guide diet, exercise or medication decisions.
Frequently confused with
- Healthy Weight Calculator — a BMI-based range for your height (Asian or WHO), generally the more current and India-relevant reference.
- BMI Calculator — a single index from height and weight, with its own adult and child/teen categories.
- Lean Body Mass Calculator — your estimated weight excluding body fat, a different quantity from either ideal or healthy weight.
Sources
Sources
- B. J. Devine (1974) — original dosing-weight formula, still the most widely cited in clinical pharmacology
- World Health Organization (WHO) and Asia-Pacific BMI classifications — used for the healthy-weight comparison on this page