How ideal body weight is calculated
Each classic ideal-weight formula starts from a base weight for a 5-foot (60-inch) frame and adds a fixed amount for every inch of height above that. The base weight and the per-inch increment change with your sex and with which formula you use, which is why men and women get different results at the same height. Enter your height and sex and this calculator runs all four formulas — Devine, Robinson, Miller and Hamwi — at once, so you see the full spread rather than a single number that pretends to more precision than these estimates carry. It also converts a healthy body-mass-index band into a weight range for your height, which is usually the more useful target.
The four formulas
Hamwi (1964) was the earliest of the set and is still used as a quick clinical rule of thumb. Devine (1974) was originally devised to standardize medication dosing and has become the most widely used ideal-weight formula in medicine. Robinson (1983) and Miller (1983) both revisited the same idea with slightly lower base weights and gentler per-inch increments, which tends to nudge their results a little below Devine's. For most heights the four land within a few kilograms of each other; seeing them side by side is a reminder that "ideal weight" is a band, not a point.
Ideal weight vs a healthy weight range
The formulas each return one figure, but a genuinely healthy weight covers a range. The healthy weight range shown here comes from a body-mass index between 18.5 and 24.9 — the band conventionally labelled "normal weight" — applied to your height. It is wider and more forgiving than any single formula, and most people are better served aiming somewhere inside it than at one exact number. If you want your BMI value itself, use the BMI Calculator.
What these numbers can't see
Ideal-weight formulas and BMI both work from height alone, so neither can tell muscle from fat or account for frame size. A muscular, athletic person can sit well above their "ideal" weight while carrying very little fat, and two people of the same height and weight can have very different body compositions. For a read on that, pair this with the Body Fat Calculator. Use the figures here as a reference point, not a verdict.