Ideal Weight Calculator

No. The four formulas we report were built for different purposes — Hamwi for nutrition tables, Devine for drug dosing, Robinson and Miller as later refinements — and they disagree by several pounds at the same height. We report a range across all four plus the BMI healthy range so you can see the spread, not pretend there's a single right answer.

Hamwi (1964) was published as a quick clinical bedside calculation. Devine (1974) was developed for gentamicin antibiotic dosing — it's the standard in pharmacology. Robinson (1983) and Miller (1983) were modified versions fit on different anthropometric data. None of them was developed for personal health or fitness goals — they were clinical or actuarial tools.

BMI 18.5–25 corresponds to a kg range that depends on your height. We include it in the breakdown because it's the World Health Organization's standard healthy-weight band and lines up well with population mortality data — though it has the same limitations as BMI elsewhere (doesn't distinguish muscle from fat, doesn't apply to pregnancy or kids).

Because the formulas don't. Two people of the same height can land at the same calculated “ideal weight” while one has 12% body fat and the other has 30%. For a number that reflects body composition rather than just height, use the body-fat or BMI calculators alongside this one — and remember that body composition matters more than the bathroom scale.

They were designed at and above 5 ft, and the slope per inch was meant to apply only to inches over 60. We extrapolate downward by subtracting the same slope per inch below 60″, which is the convention most clinical references use, but accuracy degrades for very short heights — treat short-stature outputs as rough estimates only.

It depends on the use case. Clinicians most commonly use the Devine formula for drug dosing calculations. For general population health benchmarks, BMI is preferred over any ideal weight formula. For athletic individuals, body fat percentage and lean body mass are more useful than any of these formulas. Treat the formulas as a starting point, not a definitive answer.

Not necessarily. Your goal weight should reflect your personal health markers (blood pressure, cholesterol, blood sugar, fitness level) and body composition — not just a formula. Many people feel and perform best slightly above or below their calculated ideal weight. Use the ideal weight as one data point among many.

Each formula was developed using different population data and different statistical assumptions. They typically produce results within 10-15 lbs of each other. The differences reflect that 'ideal weight' is a fuzzy concept — there's no single objectively correct answer. Looking at the range of estimates is often more useful than picking one number.

Yes, slightly. BMI defines a 'healthy weight range' (18.5-24.9 BMI) based on height, allowing for a 30-40 lb range at any given height. The ideal weight formulas calculate a single point estimate. BMI is the modern standard for population health; ideal weight formulas are still used in specific clinical contexts like drug dosing.

Significantly. People with large skeletal frames (broader shoulders, larger wrists/ankles) naturally weigh more than small-framed people at the same height. To estimate frame size: measure your wrist circumference. Small frame: less than 6.5" (women) or 6.5" (men). Medium frame: 6.5-7.0" (women) or 7.0-7.5" (men). Large frame: above these ranges. Adjust your target weight up 10% for large frame or down 10% for small frame.