What is ideal body weight — and where did it come from?
Here's a piece of history most calculators skip: the ideal body weight formulas weren't invented for dieters. Dr. BJ Devine published his in 1974 so hospital pharmacists could dose medication by body size. The Hamwi formula came from a 1964 diabetes textbook. Robinson and Miller refined the idea in 1983. They stuck around because they're simple — height and sex in, one clean number out — and that same simplicity is why they should be read loosely.
This ideal weight calculator runs all four formulas at once and shows the spread, which is more honest than pretending any single one holds the truth. It also plots the WHO healthy BMI range for your height alongside, so you can see where the formulas sit inside the much wider band that actually counts as healthy.
The four ideal weight formulas
All four share one skeleton: a base weight for the first five feet of height, plus an increment for every inch above it. They differ only in the numbers they plug in. Devine, the most widely quoted, gives men 50 kg plus 2.3 kg per inch over five feet, and women 45.5 kg plus the same increment.
For a 5 ft 10 in man that's 50 + 2.3 × 10 = 73 kg (about 161 lbs). Run the same height through Robinson, Miller, and Hamwi and you'll get answers a few kilograms either side — the calculator shows each one plus their average, and the gap between them is a useful reminder that 'ideal' was always an estimate, not a law.
One habit worth copying from clinicians: they still use these formulas today for drug dosing and ventilator settings, but they stopped using them as weight-loss targets years ago. The healthy range approach — any weight that puts your BMI between 18.5 and 24.9 — replaced the single magic number, and the healthy weight calculator is built around exactly that.
What the formulas can't see
Two inputs — height and sex — means everything else about you is invisible. Muscle mass is the big omission: a fit lifter can sit 10 kg above their Devine number with less body fat than someone sitting exactly on it. Frame size, age, and ethnicity are all absent too. If the formulas say 73 kg and you feel strong and healthy at 80, the formulas are the ones missing information.
For a picture that includes what you're actually made of, the body fat calculator and lean body mass calculator measure composition rather than assuming it.
Frequently asked questions about ideal weight
What is ideal body weight?
Ideal weight formulas (Devine, Robinson, Miller, Hamwi) estimate a target weight from height and gender. They were developed for clinical dosing and general reference.
Why do different formulas give different results?
Each formula was derived from different populations and purposes. They can differ by several kilograms — none account for muscle mass or sport-specific goals.
Is ideal weight the same as healthy weight?
Not always. WHO healthy BMI ranges are broader than a single formula number. Athletes often weigh more than formula ideal weight with lower body fat.
How do I use this ideal weight calculator?
Enter height and gender, then click Calculate to compare formula results and see how they relate to healthy BMI ranges.
Sources and further reading
- Peterson CM et al. — Universal equation for estimating ideal body weight (Am J Clin Nutr, 2016)
- World Health Organization — Healthy weight and BMI ranges
- CDC — About healthy weight
This page is for general information only and is not medical advice. Consult a qualified healthcare provider about weight goals.