Ideal Weight Calculator
Calculate your ideal weight from height and sex using the Devine formula and the WHO healthy BMI range.
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How Ideal Weight Is Calculated
This tool applies two independent references side by side rather than pretending there is one correct answer. The first is the Devine formula, published in 1955: for men, 50 kg + 2.3 kg for every inch of height over 5 feet (60 inches); for women, 45.5 kg + 2.3 kg per inch over that same 60-inch baseline. Concrete example: a man who is 5'10" (70 inches) gets 50 + 2.3×10 = 73 kg; a woman of the same height gets 45.5 + 2.3×10 = 68.5 kg. The second reference is the WHO healthy BMI range of 18.5–24.9, which converts the same height into a weight interval rather than a single number — for that 70-inch (178 cm) height, roughly 58.6–78.9 kg falls inside the healthy range.
What is easy to miss is where the Devine formula actually came from: it was developed in 1955 not as public health guidance but as a practical shortcut for calculating drug dosages in clinical medicine, where a quick estimate of lean body mass matters more than long-term health targets. It was never designed to tell a healthy adult what they "should" weigh, and using it that way stretches it well past its original purpose.
It is also not the only formula of its kind, and the others do not agree with it. The Robinson formula (1983) uses a lower base weight and a smaller per-inch increment; the Miller formula (1983) is lower still; the Hamwi formula (1964), long popular in dietetics, uses yet another set of constants. Run the same height and sex through all four and you get four different numbers, sometimes several kilograms apart — because each was fitted to a different sample population for a different clinical purpose, not because one of them is "more correct."
What to Know Before Using This Number
There is no single true ideal weight. Body composition matters as much as the scale: a muscular frame can sit well above every formula's output while remaining perfectly healthy, since muscle is denser than fat. Age, bone structure, and where fat is distributed on the body all shape what a healthy weight looks like for a specific person in a way none of these formulas captures.
Use the numbers here as a statistical reference point for a conversation, not as a personal target to hit. This tool is informational only and does not constitute medical advice — for weight goals tied to your actual health, a doctor or registered dietitian who can see your full picture is the right source, not a formula from 1955.
Frequently Asked Questions
Which result should I trust — Devine or the BMI range?
Use the BMI range as the practical guide: anywhere inside it is considered healthy. The Devine number is a single clinical reference point used mainly for medication dosing.
Does age affect ideal weight?
The formulas here use only height and sex. In practice, slightly higher BMI values in older adults are not associated with worse health, so treat the range flexibly with age.
Is ideal weight different for athletes?
Muscular people can healthily exceed the range since muscle weighs more than fat. Body-fat percentage is a better indicator for athletes.
Why do Devine, Robinson, Miller and Hamwi give different numbers for the same person?
Each formula was built from a different reference population for a different original purpose, so they use different base weights and per-inch increments. None of them is "the" correct answer — they are different statistical estimates that happen to cluster in a similar range, which is itself the useful signal.
Was the Devine formula designed for general health advice?
No. It was developed in 1955 specifically to help clinicians estimate drug dosing, not to define a healthy weight target for the public. It is still useful as a quick reference point, but treat the BMI range as the more health-relevant number.
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