Ideal Weight Calculator — Four Formulas, One Real Answer
Most ideal weight tools give you one number from one formula. This calculator runs all four clinically validated formulas — Devine, Robinson, Miller, and Hamwi — alongside your healthy BMI range, and gives you a personalised HealthIQ Weight Score out of 100.
Know your ideal weight — now find your calorie plan
Ideal weight gives you the destination. Calorie deficit gives you the route.
The Honest Truth About Ideal Weight Calculators
Here is something most ideal weight calculators will not tell you: the formulas they use were invented to calculate drug dosages. The Devine formula — the one hospitals still use today — was published in 1974 to help doctors dose aminoglycoside antibiotics. It was never designed to be a personal weight target.
That does not make these numbers useless. They give you a reasonable reference range based on your height and sex. But treating them as a precise personal target misses the point. Use the range as context, not a verdict.
Clinical note: Hospitals still use the Devine formula today for ventilator settings and medication dosing — not weight goals. Lung volume scales with lean body mass, and the formula approximates that. This is why the ideal weight your doctor calculates may differ from your personal health goal.
The Four Formulas — What Each One Actually Is
Devine Formula (1974)
The most widely cited. Men: 50 kg plus 2.3 kg per inch over 5 feet. Women: 45.5 kg plus 2.3 kg per inch over 5 feet. Still used in ICUs worldwide for drug and ventilator calculations.
Robinson Formula (1983)
A refinement of Devine. Men: 52 kg plus 1.9 kg per inch over 5 feet. Women: 49 kg plus 1.7 kg per inch over 5 feet. Produces slightly different results at extreme heights.
Miller Formula (1983)
Men: 56.2 kg plus 1.41 kg per inch over 5 feet. Women: 53.1 kg plus 1.36 kg per inch over 5 feet. Consistently the lowest estimates of the four. Some researchers consider it most appropriate for smaller-framed individuals.
Hamwi Formula (1964)
The oldest formula here. Men: 48 kg plus 2.7 kg per inch over 5 feet. Women: 45.5 kg plus 2.2 kg per inch over 5 feet. Widely used in clinical nutrition for hospitalised patient feeding calculations.
Why Frame Size Changes Everything
Two people can be exactly the same height and sex but have meaningfully different bone densities. A large-framed person naturally carries more mass. The standard clinical adjustment is plus or minus 10% for small and large frames — applied to all four formulas here. To measure your frame size: wrap your thumb and index finger around your wrist. If they overlap, small-framed. If they just touch, medium. If they cannot reach, large.
What These Numbers Cannot Tell You
None of these formulas accounts for muscle mass. A 90 kg person at 20% body fat training seriously is in a completely different health position than a 90 kg sedentary person at 35% body fat — even if both get the same output here. For a complete picture, use this alongside the Body Fat Score Calculator and the BMI Calculator.
| Formula | Developed For | Relative to Others | Most Useful When |
|---|---|---|---|
| Devine | Drug dosing (1974) | Middle range | Standard clinical reference |
| Robinson | Clinical refinement (1983) | Slightly lower | Average height adults |
| Miller | Insurance tables (1983) | Lowest of four | Smaller-framed individuals |
| Hamwi | Clinical nutrition (1964) | Highest of four | Taller / larger frames |
| BMI Range | WHO classification | Widest range | General goal-setting |