The four formulas
| Formula | Base (men) | Per inch over 5 ft | Base (women) | Per inch over 5 ft |
|---|---|---|---|---|
| Devine (1974) | 50.0 kg | +2.3 kg | 45.5 kg | +2.3 kg |
| Robinson (1983) | 52.0 kg | +1.9 kg | 49.0 kg | +1.7 kg |
| Miller (1983) | 56.2 kg | +1.41 kg | 53.1 kg | +1.36 kg |
| Hamwi (1964) | 48.0 kg | +2.7 kg | 45.5 kg | +2.2 kg |
All four share the same shape — a base weight at 5 feet (152.4 cm) plus an increment per inch above it — but disagree on the increments, which is why we show every result plus their average. The Devine formula is the one still used clinically for medication dosing and ventilator settings.
A healthier way to read the number
There is no single ideal weight. A more defensible target is the healthy BMI band (18.5–24.9), which for any height spans a 15+ kg range — wide enough to accommodate different builds and muscle mass. Use the formula average as a midpoint reference, not a finish line: body composition, waist size, fitness, blood markers, and how you feel matter more than one scale number.
Why the formulas exist at all
Hamwi (1964) published his rule for quick bedside dosing estimates; Devine (1974) refined it for gentamicin dosing; Robinson and Miller (1983) re-fitted the coefficients against actuarial data. Their persistence in fitness culture is an accident of history — treat them as the clinical shorthand they are.
This tool provides general estimates for educational purposes and is not medical advice. Consult a healthcare professional for guidance specific to you.
Frequently asked questions
Which ideal weight formula is most accurate?
None is 'accurate' in a health sense — they're height-based conventions. Devine is the clinical standard for drug dosing; Robinson often lands closest to the middle of the healthy BMI range. The average of all four is a reasonable single reference.
Why is my ideal weight so far from my actual weight?
The formulas ignore frame size, muscle mass, and age. A muscular 175 cm man can be perfectly healthy 15 kg above his Devine weight. Check where you sit in the healthy BMI range and consider body fat percentage before drawing conclusions.
Do these formulas work for very tall or short people?
They degrade at the extremes. Below 5 ft (152 cm) the 'per inch' logic breaks down entirely, and for very tall people the linear increments under- or over-shoot. The BMI range handles extreme heights more gracefully.
What about frame size — small, medium, large?
Older tables adjusted ±10% for frame size, often judged by wrist circumference. Evidence for those adjustments is thin, but they capture something true: skeletal breadth varies, and a single number can't fit everyone.
Should I diet down to my ideal weight?
Not automatically. If you're within the healthy BMI band, improving fitness and body composition usually beats chasing a formula number. If you're well above it, aim for gradual loss (0.25–0.5 kg/week) toward the top of the healthy range first.