Which formula is 'correct'?

None is more correct than the others — all four are height-only regression formulas originally developed for estimating drug dosing weight in clinical settings, later adopted broadly as general weight references. Devine is the most commonly used default today.

Why do the formulas give different numbers for the same height?

Each was fit to a different reference population and era, so the per-inch weight increment differs (e.g. Devine adds 2.3 kg/inch for men, Miller adds only 1.41 kg/inch). Expect a few kilograms of spread between formulas — that spread is normal, not an error.

Why does height have such a big effect?

All four formulas are linear in height: they start from a base weight at 5 feet (152 cm) and add a fixed amount per inch above it. That's also why none of them handle heights well outside typical adult ranges — treat results for very short or very tall inputs as rough only.

Ideal Body Weight Calculator

Estimate ideal body weight from height and sex using the Devine, Robinson, Miller or Hamwi formula, toggled in one tool, with results in kg and lb.

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Formula: Devine (men): 50 kg + 2.3 kg per inch of height over 5 ft; other formulas shown in the explainer

Worked examples

Man, 180 cm, Devine formula
Devine (1974) is the most widely used formula in clinical and fitness contexts, and the default here.
Woman, 165 cm, Robinson formula
Robinson (1983) generally gives a slightly lower target than Devine for the same height.
Man, 70 in (imperial), Hamwi formula
Hamwi (1964) is the oldest of the four and was originally published in pounds; both kg and lb are shown regardless of the input unit.

What "ideal weight" means here

These formulas estimate a reference body weight from height and sex alone. They were originally developed for clinical purposes — mainly to standardize drug dosing calculations, where a consistent weight reference matters more than individual body composition — and were later adopted broadly as general weight references in fitness and wellness contexts. This tool keeps that consumer-fitness framing: a general reference point to compare against, not a personalized health target.

The four formulas

Devine (1974) is the most widely used today and the default here.
Robinson (1983) generally gives a slightly lower number than Devine for the same height.
Miller (1983) uses the smallest per-inch increment of the four, producing the most conservative estimates.
Hamwi (1964) is the oldest, originally published in pounds using a simple "106 lb + 6 lb per inch over 5 feet" rule for men (100 + 5 for women); this tool converts that to kilograms internally so all four formulas are comparable side by side.

All four are toggled in one tool rather than split into four near-identical pages, since they take identical inputs and estimate the same thing with different constants.

Why the formulas disagree

Each was fit to a different reference population in a different era, so the weight added per inch of height above a 5-foot baseline differs — Devine adds 2.3 kg per inch for men, Miller only 1.41 kg per inch. A spread of a few kilograms between formulas for the same height is normal and doesn't mean any one of them is wrong; they're simply different historical estimates of the same general idea.

How to use the result

Results are shown in both kilograms and pounds regardless of which unit you entered, since many people search for this figure in one unit but think in the other. Use the number as one general reference point, not a target to hit exactly — these formulas were built for dosing calculations and clinical shorthand, not for evaluating whether an individual's weight is healthy for them.

Limits

None of the four formulas account for muscle mass, frame size, or body composition. A heavily muscled person will reasonably and healthily weigh well above what any of these formulas suggest, while someone with a genuinely larger or smaller frame will too. They also weren't designed for, and don't handle well, heights well outside typical adult ranges — treat results near the edges of the input range as illustrative only. This tool is informational and not a substitute for advice from a qualified healthcare provider.

Frequently asked questions

Which formula is 'correct'?: None is more correct than the others — all four are height-only regression formulas originally developed for estimating drug dosing weight in clinical settings, later adopted broadly as general weight references. Devine is the most commonly used default today.
Why do the formulas give different numbers for the same height?: Each was fit to a different reference population and era, so the per-inch weight increment differs (e.g. Devine adds 2.3 kg/inch for men, Miller adds only 1.41 kg/inch). Expect a few kilograms of spread between formulas — that spread is normal, not an error.
Is this the weight I should aim for?: Treat it as one general reference point, not a target. These formulas don't account for muscle mass, frame size or body composition — a heavily muscled person will reasonably weigh more than the formula suggests while still being lean and healthy.
Why does height have such a big effect?: All four formulas are linear in height: they start from a base weight at 5 feet (152 cm) and add a fixed amount per inch above it. That's also why none of them handle heights well outside typical adult ranges — treat results for very short or very tall inputs as rough only.

These calculators give general estimates from published formulas. They are not medical advice and do not account for your individual health; talk to a qualified professional before changing your diet or training.