Ideal Weight
Calculate ideal body weight using multiple formulas
These calculators provide general information only and are not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.
How to use Ideal Weight
- 1Select sex and unit system, since the coefficients differ by sex.
- 2Enter your height; some formulas also ask for age or frame size.
- 3Compare the range produced by several formulas and note the systematic gaps between them.
The different ideal body weight formulas
Devine (men) = 50 + 0.9 × (height cm − 152.4); Hamwi (women) = 45.5 + 0.9 × (height cm − 152.4)Ideal body weight is not a single standard but a family of historical equations. The Devine formula, from 1974, was originally designed to estimate anaesthetic and drug dosages and was later borrowed for everyday use. Hamwi and Robinson came slightly earlier and give similar results. All share the shape of a base value plus 0.9 kg for every centimetre above 152.4 cm, which is five feet.
Two caveats matter. First, these equations were built decades ago mainly on Western samples and ignore age, frame size and muscle mass, so they tend to run 5% to 10% low for Asian populations. Second, they serve different purposes: Devine for dosing, BMI ranges for health screening, body fat for composition. Treat ideal weight as a reference band, roughly plus or minus 10% around the formula results, rather than a number you must hit.
| Formula | Man 175 cm | Woman 165 cm | Note |
|---|---|---|---|
| Devine (1974) | ≈ 70.4 kg | ≈ 56.7 kg | Most used for drug dosing |
| Hamwi (1964) | ≈ 70.3 kg | ≈ 56.7 kg | Close to Devine |
| Robinson (1983) | ≈ 68.0 kg | ≈ 56.9 kg | Slightly lower for men |
| Miller (1983) | ≈ 69.4 kg | ≈ 56.8 kg | Between the two |
Ideal weight by formula (man 175 cm, woman 165 cm)
Frequently asked questions
Does ideal weight match a normal BMI?
They correspond roughly but not exactly. Devine's output for most heights converts to a BMI around 21 to 23, the lower-middle part of the normal band, while the normal BMI range spans 18.5 to 24.9. At a given height, therefore, normal BMI is a much wider target than ideal weight; they are simply different reference frames.
How should athletes estimate ideal weight?
These formulas do not apply. Muscle is denser than fat, so strength athletes often exceed the predicted weight by 15% to 25% while carrying low body fat and healthy metabolic markers. They should look at body fat percentage and waist circumference instead. Equally, older adults who have lost muscle may hit the target weight while carrying too much fat.
Why do the formulas disagree?
They were fitted to different samples in different eras for different purposes. Devine and Hamwi differ by under 1%, while Robinson and Miller run 2 to 3 kg lower for men. That spread is far smaller than natural variation between individuals, so arguing over which to use matters less than viewing the results as a band.
Is being below ideal weight always healthier?
No. A BMI under 18.5 is associated with reduced immunity, bone loss, menstrual disruption and malnutrition risk. Low weight often comes with low muscle mass, and muscle underpins metabolic health and independence later in life. The aim is moderate body fat with adequate muscle, not the smallest number on the scale.