Ideal Weight Calculator
See your ideal body weight from four established formulas, side by side.
Ideal Weight Calculator — your inputs
- Sex
- Male
- Height
- 180 cm
- Unit system
- Metric
Key takeaways
- These formulas were built for drug dosing, not for health goals. Devine's 1974 equation exists so anaesthetists could size a dose safely.1
- All four give a single number. Your body does not have a single correct weight — it has a range, and the range is wide.
- The four disagree by several kilograms at the same height. That disagreement is the most honest thing on this page.
- For a health target, use the Healthy Weight Calculator instead — a range derived from BMI is a better answer to the question you are actually asking.
- None of them account for build, muscle mass or body composition. A powerlifter and a sedentary person of the same height get the same number.
How to use this calculator
Choose your unit system and enter your sex and height.
The calculator shows four formula estimates, their average, and the healthy-BMI window.
Understanding your result
These four formulas each estimate a 'desirable' weight for a given height and sex, derived from mid-20th-century clinical and insurance data.
Because they disagree, we show all four plus their average. The healthy-BMI window (18.5–24.9) is shown for cross-reference.
Where these formulas came from
This is the calculator whose history most changes how you should read it. None of the four equations was designed to tell anyone what to weigh.
In 1974 B.J. Devine published a formula for estimating ideal body weight so that drug doses — particularly for medications distributed through lean tissue rather than fat — could be calculated safely in patients of unusual size.1 It was published without derivation or supporting data, in a clinical pharmacy journal, as a practical rule of thumb. Robinson, Miller and Hamwi followed with their own variants over the next decade, each fitting slightly different data.23 Pai and Paloucek later traced the lineage and found that all of them descend from mid-century insurance height-weight tables rather than from any study of health outcomes.4
What this means for you
"Ideal body weight" is a term of art in pharmacology that unfortunately sounds like a lifestyle recommendation. These numbers are useful for what they were built for and are a poor target for anyone deciding what to weigh.
The four formulas, and why they disagree
| Formula | Men | Women |
|---|---|---|
| Hamwi (1964) | 48.0 kg + 2.7 kg per inch over 5 ft | 45.5 kg + 2.2 kg per inch over 5 ft |
| Devine (1974) | 50.0 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Robinson (1983) | 52 kg + 1.9 kg per inch over 5 ft | 49 kg + 1.7 kg per inch over 5 ft |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft |
Notice the structure they share: a base weight at five feet, plus a fixed increment per inch. That linear form is the source of their main weakness. Real bodies do not scale linearly with height, so the formulas diverge most at the extremes — for someone very tall or very short, the four answers can differ by ten kilograms or more.
- Hamwi75.6 kg
- Devine73 kg
- Robinson71 kg
- Miller70.3 kg
| Method | Value (kg) |
|---|---|
| Hamwi | 75.6 |
| Devine | 73 |
| Robinson | 71 |
| Miller | 70.3 |
A five-kilogram spread between four equally published formulas is not a flaw in any one of them. It is what happens when four groups fit simple rules to different populations for a purpose that never required precision. Treat the spread as the confidence interval it effectively is.
What to use instead
If the question is "what should I weigh for my health?", a range beats a number, and the evidence supports a fairly wide one. The largest analysis of body weight and mortality — 239 studies, roughly ten million people — found the lowest mortality between about 20 and 25 kg/m², which at 178 cm is a span of some sixteen kilograms.5
- For a health target, use the Healthy Weight Calculator. It converts the normal BMI band into weight for your height and gives you the range rather than a point.
- For body composition, the Body Fat Calculator answers what the scale cannot: how much of the weight is fat.
- For muscle, the Lean Body Mass Calculator tells you what you are trying to keep while losing weight.
- For clinical dosing, these formulas are exactly right, and that is what they are here for.
Why we show all four rather than picking one
Most calculators show one formula and call it your ideal weight, which implies a precision that does not exist. Showing the disagreement is more useful than hiding it behind a single confident number.
Terms used on this page
- Ideal body weight (IBW)
- A clinical estimate used mainly for drug dosing and ventilator settings. Despite the name, it is not a recommendation about what to weigh.
- Adjusted body weight
- IBW plus a fraction of the excess over it, used for dosing drugs that partly distribute into fat tissue. A refinement that exists precisely because IBW alone is too crude for some medications.
- Insurance tables
- Mid-twentieth-century height-weight charts compiled by life insurers from policyholder data. The ancestor of every formula on this page, and never a representative sample of the population.
The formula
- Man, height 180 cm ≈ 5 ft 10.8 in → 10.8 in over 5 ft
- Devine: 50.0 + 2.3×10.8 = 50.0 + 24.84
Source: Robinson, Miller, Devine, Hamwi. Published clinical/scientific formula.
Limitations
- These formulas come from population averages and don't account for frame size, muscle mass, or individual variation.
- Treat the result as a reference range, not a target to hit exactly.
- They are less reliable at extreme heights.
References
- 1.Determination of ideal body weight for drug dosage calculations. Devine, B.J., Drug Intelligence and Clinical Pharmacy 8:650–655, 1974.
- 2.Determination of ideal body weight for drug dosage calculations (revised). Robinson et al., American Journal of Hospital Pharmacy 40(6):1016–1019, 1983.
- 3.Estimation of ideal body weight. Miller et al., Drug Intelligence and Clinical Pharmacy 17(3):219–224, 1983.
- 4.Ideal body weight equations and their derivation. Pai & Paloucek, Annals of Pharmacotherapy 34(9):1066–1069, 2000.
- 5.Body-mass index and all-cause mortality: meta-analysis of 239 prospective studies. Global BMI Mortality Collaboration, The Lancet 388(10046):776–786, 2016.
Frequently asked questions
Related calculators
BMI Calculator
Calculate your Body Mass Index and see where you fall on the WHO weight categories.
Open calculatorHealthy Weight Calculator
Find the healthy weight range for your height and how far you are from it.
Open calculatorLean Body Mass Calculator
Estimate your lean body mass from three published formulas.
Open calculatorRelated articles
What Is a Healthy BMI? Understanding the WHO Categories
Where the 18.5–24.9 range came from, what the categories above and below it actually mean, and how much weight to put on the number.
Read articleIdeal Weight Formulas Compared: Devine, Robinson, Miller and Hamwi
Four formulas, four different answers, all from the same height. Where they came from, why they disagree, and what to use instead of any of them.
Read articleIdeal Weight vs. Healthy Weight: Which Target Should You Use?
One is a number invented for drug dosing. The other is a range derived from mortality data. They are not the same thing, and only one of them is a sensible goal.
Read articleNot medical advice. This calculator is for general informational purposes only and is not a substitute for professional medical guidance. Always consult a qualified healthcare provider before making decisions about your health. Read the full medical disclaimer.
Printed from mystatura.com — for general information only, not medical advice.