Ideal Weight Calculator — Healthy Weight Range

What this calculates, and what it cannot

Enter your height and sex and this returns an ideal body weight estimate from several published formulas, plus a healthy weight range derived from BMI. Before the numbers, one thing is worth saying plainly: there is no single ideal weight for a person of a given height. These formulas were built for clinical purposes, not for setting personal goals, and they should be read as a broad reference band rather than a target.

The formulas

All four classic formulas share a structure — a base weight at 5 feet, plus a fixed increment per inch above that. They differ only in the constants, which is a reminder of how much they are conventions rather than discoveries.

Formula	Men	Women	Year
Devine	50.0 kg + 2.3 kg per inch over 5 ft	45.5 kg + 2.3 kg per inch over 5 ft	1974
Robinson	52.0 kg + 1.9 kg per inch over 5 ft	49.0 kg + 1.7 kg per inch over 5 ft	1983
Miller	56.2 kg + 1.41 kg per inch over 5 ft	53.1 kg + 1.36 kg per inch over 5 ft	1983
Hamwi	48.0 kg + 2.7 kg per inch over 5 ft	45.5 kg + 2.2 kg per inch over 5 ft	1964

The Devine formula is the most cited, though it was never intended for this. It was devised to calculate drug dosages — specifically to estimate lean mass for medications where dosing by total body weight would overdose a heavier patient. It was published without supporting data and became a standard largely through repetition.

A worked example

A man of 178 cm, which is 70.1 inches, so 10.1 inches over 5 feet:

Devine: 50 + (2.3 x 10.1) = 73.2 kg
Robinson: 52 + (1.9 x 10.1) = 71.2 kg
Miller: 56.2 + (1.41 x 10.1) = 70.4 kg
Hamwi: 48 + (2.7 x 10.1) = 75.3 kg

A spread of nearly 5 kg between formulas for the same person, all equally "ideal". That spread is the honest answer to how precise this concept is.

The BMI healthy range

A more useful framing than a single number is the weight range corresponding to a BMI of 18.5 to 24.9:

lower bound = 18.5 x height in metres squared
upper bound = 24.9 x height in metres squared

For 178 cm that is 58.6 kg to 78.9 kg — a 20 kg band, all of it classified as healthy. Where you sit within it depends on build and muscle mass, and moving from one end to the other is not in itself a health improvement. Our BMI calculator works the same relationship from the other direction.

Why these numbers mislead

They ignore body composition entirely. A muscular athlete will exceed every ideal weight figure while carrying very little fat. Weight alone cannot distinguish muscle from fat, and the health implications are opposite.
They ignore frame size. Skeletal build varies enough that two people of identical height can healthily differ by several kilograms before any soft tissue is considered.
They derive from narrow populations. The source data was largely mid-20th-century North American and European adults, and the formulas transfer poorly to other body types and ancestries.
They are linear, and bodies are not. A fixed increment per inch fits poorly at the extremes, understating healthy weight for very tall people and overstating it for very short ones.
They say nothing about where fat sits. Visceral fat around the organs carries far more metabolic risk than the same mass on hips and thighs, which is why waist measurement predicts outcomes better than weight does.

Better things to measure

If the goal is health rather than a number on a scale, these are more informative: waist circumference (raised risk above roughly 94 cm for men and 80 cm for women, with lower thresholds for South Asian populations), waist-to-height ratio (keeping your waist under half your height is a simple and surprisingly robust guide), body fat percentage, and simple functional markers such as resting heart rate, blood pressure and how you handle a flight of stairs.

This is an estimate, not medical advice. If you are considering significant weight change, particularly if you have a medical condition, are pregnant, or have any history of disordered eating, that conversation belongs with a doctor or dietitian who can see the whole picture.

Frequently asked questions

Why do the formulas disagree with each other?

Because they are conventions built on different datasets and assumptions, not measurements of a real quantity. For a 178 cm man they span nearly 5 kg. Treat the spread as the honest margin of error on the whole concept.

Which formula should I use?

For a general reference, the BMI-derived healthy range is more defensible than any single formula, because it gives a range rather than a false point estimate. Devine remains the standard in clinical settings, but it was designed for drug dosing rather than for personal goals.

My weight is above the ideal figure. Is that a problem?

Not necessarily. These formulas cannot distinguish muscle from fat, do not account for frame size, and come from a narrow source population. Waist circumference, body fat percentage and clinical markers such as blood pressure tell you far more than a height-based number can.

Do these work for children or during pregnancy?

No. Children are assessed against age-and-sex-specific growth percentiles, not adult formulas, and appropriate weight gain in pregnancy is guided by starting BMI and monitored by a clinician. Do not apply these figures in either case.

Is there an ideal weight for athletes?

Not one these formulas can produce. Athletes carrying substantial muscle routinely exceed every ideal weight figure while being extremely healthy. Body composition measurement is the appropriate tool where performance and health both matter.