Ideal Weight Calculator — Five Formulas, One Clear Answer
Ideal body weight (IBW) is a clinically useful estimate of the weight at which a person of a given height is likely to have the best health outcomes. Unlike BMI — which tells you whether your current weight falls in a healthy range — IBW gives you a concrete target weight based on your height and gender.
Five widely used IBW formulas were developed between 1964 and 1983, each from a different study population and clinical context. This calculator runs all five simultaneously and shows you the full range, so you can see both the consensus and the spread between formulas.
IBW is widely used in clinical medicine for dosing medications, calculating nutritional needs, and setting weight-loss targets. It is not a strict prescription — it's a useful reference point alongside BMI, body fat percentage, and individual health context.
The Five IBW Formulas Explained
All formulas are based on height above a baseline of 5 ft (152.4 cm), with a per-inch adjustment for each additional inch of height.
Originally developed for drug dosing calculations, the Devine formula became the default IBW equation in pharmacology and clinical nutrition. It remains the most widely cited despite being developed without a robust dataset.
A revision of the Devine formula published by Robinson et al. in 1983. Uses slightly different base weights and per-inch increments, and tends to give somewhat higher estimates for females than Devine.
The Miller formula generally produces the highest IBW estimates of the five, particularly for taller individuals. It uses higher base weights and smaller per-inch increments, resulting in a flatter curve across heights.
The oldest of the five formulas, the Hamwi method was developed for clinical nutrition assessment in 1964. It uses the steepest per-inch increment for males, which means it produces higher estimates for taller men than the other formulas.
Rather than a single point estimate, this method derives a weight range from the WHO-defined healthy BMI range (18.5–24.9). It is gender-neutral and produces a range rather than a single value, making it useful as a reality check against the point estimates above.
How the Formulas Compare at Common Heights
The five formulas agree closely at average heights but diverge at the extremes. Here's how they compare for males at selected heights:
| Height | Devine | Robinson | Miller | Hamwi |
|---|---|---|---|---|
| 160 cm (5'3") | 52.3 kg | 53.9 kg | 59.1 kg | 51.6 kg |
| 170 cm (5'7") | 65.6 kg | 65.7 kg | 67.7 kg | 67.8 kg |
| 175 cm (5'9") | 71.7 kg | 71.1 kg | 71.6 kg | 75.1 kg |
| 180 cm (5'11") | 77.8 kg | 76.5 kg | 75.5 kg | 82.5 kg |
| 188 cm (6'2") | 87.6 kg | 85.0 kg | 82.9 kg | 93.6 kg |
Notice that at 170–175 cm the formulas converge closely, while at the height extremes the spread can be 10–15 kg. This is why looking at the full range — rather than a single formula — gives a more useful picture.
Limitations of Ideal Weight Formulas
IBW formulas are useful reference tools, but they have important limitations:
How to Use This Ideal Weight Calculator
- Select your gender — all five IBW formulas use different constants for males and females.
- Choose your unit system — metric (cm/kg) or imperial (ft·in/lb).
- Enter your height — use your accurate standing height without shoes.
- Enter your current weight (optional) — enables the weight-to-target note and your current BMI calculation.
- Click "Calculate Ideal Weight" — results show the consensus range, all five formula values, and the BMI-based healthy weight range.
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