Ideal Weight Calculator
Free ideal body weight calculator using the Devine formula — the reference equation in clinical pharmacology. Metric units (kg, cm). Runs in your browser.
Type in your sex and height. The calculator returns the Devine ideal body weight — the reference adult weight for that height, still widely used in clinical pharmacology.
The formula
Male: 50.0 kg + 2.3 kg per inch above 5 ft
Female: 45.5 kg + 2.3 kg per inch above 5 ft
5 ft = 60 inches = 152.4 cm. Each cm above 152.4 cm adds about 0.91 kg.
For a 180 cm male: (180 − 152.4) ÷ 2.54 ≈ 10.87 inches over 5 ft;
ideal = 50 + 2.3 × 10.87 ≈ 75.0 kg.
What this is and isn’t
Devine was developed in 1974 for drug-dosing calculations — many medications are dosed by lean body mass, and a reproducible height-only estimate is useful when you can’t directly measure composition. It is not a health target. The calculator returns a single number; real-life adult weight can sit ±10% above or below the Devine value without anything being wrong.
Heavily muscled people are routinely 10–20% over Devine because the formula doesn’t know about lean mass. Athletes routinely “fail” Devine while being healthier than average.
The other classic formulas
| Formula (year) | Male @ 180cm | Female @ 165cm |
|---|---|---|
| Hamwi (1964) | ~74.5 kg | ~58.7 kg |
| Devine (1974) | ~75.0 kg | ~56.9 kg |
| Robinson (1983) | ~72.6 kg | ~56.7 kg |
| Miller (1983) | ~71.5 kg | ~56.2 kg |
All four sit within a ~5 kg range. Devine has the most clinical traction.
Use it as a reference point
Pair the Devine number with a body-composition measurement (DEXA, body-fat calliper, waist circumference) for an actual health read. Single-number “ideal weight” is a starting point, not a diagnosis.
Worked examples
-
Male, 180 cm
Ideal weight: 75.0 kg.
-
Female, 165 cm
Ideal weight: 56.9 kg.
Frequently asked questions
What formula does this use?
Devine (Drug Intell Clin Pharm 1974). Male: 50.0 kg + 2.3 kg per inch over 5 ft; Female: 45.5 kg + 2.3 kg per inch over 5 ft. Of the four classic formulas (Hamwi 1964, Devine 1974, Miller 1983, Robinson 1983), Devine is the one still most cited as the reference — particularly in clinical drug-dosing contexts.
Is \"ideal weight\" actually ideal?
No — and the name is misleading. Devine and the related formulas were originally derived for drug-dosing calculations, not as health targets. They predict a reasonable adult weight for a given height, on average, but they do not account for body composition, frame size, age, or musculature. A heavily muscled person can be well above their "ideal" without being unhealthy.
Why are there multiple ideal-weight formulas?
Different authors used different populations and assumptions. Robinson (1983) is slightly lighter than Devine; Miller (1983) is lighter again; Hamwi (1964) is closest to Devine. The clinically-used range is roughly Devine ± 10%.
How does this differ from BMI?
BMI takes your weight and tells you the category; Devine takes your height and tells you a reference weight. They look at the same question from opposite sides. Use both as rough orientation — neither is a substitute for body-composition measurement (DEXA, body-fat calliper, waist circumference).
Is there a metric-native ideal-weight formula?
Devine's "2.3 kg per inch over 5 ft" is awkward in metric, but the formula converts cleanly: each cm of height above 152.4 cm adds about 0.91 kg. The math is unchanged — it's just an artifact of US clinical history.
Related calculators
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Health & FitnessTDEE & BMR Calculator
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