Compare four ideal-weight formulas
This calculator compares the Devine, Robinson, Miller and Hamwi adult reference-weight equations. It shows every result, their range, and a simple four-formula average in pounds or kilograms.
How to use the Ideal Weight Calculator
- Enter adult height from 120 to 230 cm, or the equivalent in feet and inches.
- Select the sex coefficient used by the classic equations.
- Choose pounds or kilograms for results.
- Compare all four formulas instead of treating one estimate as exact.
Ideal weight formulas
Each equation starts with a reference weight at 5 feet and adds weight for every inch above 5 feet.
| Formula | Male equation | Female equation |
|---|---|---|
| Devine | 50 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in |
| Robinson | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in |
| Miller | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
| Hamwi | 48 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in |
How to interpret the results
The formula range shows how much reasonable historical equations can disagree for the same height and sex coefficient. The average is a convenient summary, not a scientifically superior target.
Actual healthy weight depends on body composition, waist measurement, age, health history, ethnicity, medications, fitness and personal circumstances. A height-only equation cannot evaluate those factors.
Worked example
For a 5 ft 9 in male equation, the four methods produce different reference weights because their starting values and per-inch additions differ. The calculator converts each result to the selected unit, identifies the lowest and highest values, and calculates the arithmetic average.
Limitations and appropriate use
These equations start from a 5-foot baseline. Results below 5 feet are mathematical extrapolations and should be interpreted cautiously. They are not body-fat measurements and should not be applied to children, pregnancy, or as compulsory weight-loss goals.
Frequently asked questions
Which ideal-weight formula is best?
No single equation is best for every person. Showing several formulas makes their uncertainty visible.
Why do the formulas give different results?
They use different 5-foot starting weights and different additions per inch.
Is the average my ideal weight?
No. It is only the arithmetic average of four historical reference equations.
Can adults shorter than 5 feet use the calculator?
Yes, but the result is extrapolated below the formulas' original 5-foot baseline and is therefore less reliable.
Do the formulas account for body frame or muscle?
No. They use height and a sex-specific coefficient only.
Can children or pregnant people use this calculator?
No. Growth and pregnancy require different assessment approaches.