Ideal Body Weight Calculator
Calculate ideal body weight (IBW) from height and sex using the Devine, Hamwi, Robinson, Miller and Peterson formulas side by side, with body-frame adjustment, a range and midpoint, and a healthy BMI weight range.
Input
Four of the five formulas are sex-specific. Peterson (2016) is not, so it ignores this.
In centimeters or inches, per the Units selection above. 5 ft 10 in = 70 in = 177.8 cm.
The Hamwi ±10% frame convention. Leave it on medium if you are unsure.
Output
| Method | Ideal weight |
|---|---|
| No data yet | |
Clinical reference figure, not medical advice. Ideal body weight is used for drug dosing, ventilator settings and nutrition targets — it is not a healthy or target weight for an individual, and it accounts for neither muscle mass nor body composition. Talk to a clinician before acting on any of these numbers.
Guides
Ideal body weight (IBW) is a clinical reference figure derived from height and sex. It is not a goal weight, and it is not BMI — it exists mainly because several drug dosages, ventilator tidal volumes and nutritional targets are calculated from it rather than from actual body weight.
The catch is that there is no single IBW number. At least five formulas are in published use, they were fitted decades apart, and at the same height they can disagree by 5–6 kg. This calculator runs all five at once so you can see the spread instead of trusting whichever one a given website happens to use.
How to use it
- Pick Sex. Four of the five formulas are sex-specific; Peterson (2016) is not and ignores this setting.
- Pick Units — metric (height in cm, results in kg) or imperial (height in inches, results in lb). Both units are shown either way, the selected one first.
- Enter your Height. For imperial, convert feet and inches first: 5 ft 10 in = 70 in.
- Optionally set Body frame. Small subtracts 10%, large adds 10%, medium leaves the figures alone.
The results table lists each formula's answer, the range across all five, the midpoint of that range, and — for context — the weight range that would put you in the WHO healthy BMI band (18.5–25) at your height.
The formulas
All four of the classic formulas are linear in inches over 5 feet:
| Formula | Men | Women |
|---|---|---|
| Hamwi (1964) | 48.0 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in |
| Devine (1974) | 50.0 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in |
| Robinson (1983) | 52.0 kg + 1.9 kg/in | 49.0 kg + 1.7 kg/in |
| Miller (1983) | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
Peterson (2016) works differently: it is sex-neutral and anchored to a target BMI rather than to 5 feet, using IBW = 2.2 × BMI + 3.5 × BMI × (height in m − 1.5). This tool uses BMI 22, the midpoint of the healthy band.
Which formula should I use?
Devine, unless something tells you otherwise. It is the one embedded in most drug-dosing references, which is why it survives — it was proposed for gentamicin dosing, not as a health target. Robinson and Miller are later refits of Devine and generally return lower numbers; Hamwi is the oldest and the most generous at tall heights; Peterson is the newest and the only one that does not treat 5 feet as a special anchor.
Why does the tool warn me below 5 feet?
The four linear formulas add or subtract per inch from a base weight set at exactly 60 inches. Below that they are extrapolating outside the range they were fitted on, so the figures keep falling in a straight line where real reference weights do not. They are still shown, with a note. Heights outside 130–230 cm are refused outright — these are adult references and mean nothing for children.
What does body frame actually mean?
The Hamwi ±10% convention, traditionally judged from wrist circumference or elbow breadth relative to height. It is a rough correction for skeletal size, not a measure of body composition, and it scales every formula equally — so it shifts all the numbers without changing which formula says what. Leave it on medium if you are unsure.
Related tools
For the metric almost everyone actually wants — a classification of your current weight — use the BMI Calculator. To estimate composition rather than a target weight, the Body Fat Calculator uses the US Navy tape-measure method. For daily calorie targets, see the BMR & TDEE Calculator.
Privacy
Everything runs in your browser. Your height, sex and frame selection are never sent to a server, logged or stored.