Ideal Weight Calculator
Compare ideal body weight from the Devine, Robinson, Miller and Hamwi formulas with the healthy BMI range for your height, in kg or lb.
Estimate based on published formulas, not medical advice. Talk to a health professional about your situation.
These formulas were built for heights of 5 ft (152.4 cm) and above. Below that, the results are a straight-line extrapolation and are even less reliable.
- Range of the four formulas
- –
- Healthy BMI range (18.5–24.9) at your height
- –
| Formula | Equation | Reference weight |
|---|---|---|
| Devine (1974) | – | |
| Robinson (1983) | – | |
| Miller (1983) | – | |
| Hamwi (1964) | – |
These figures are rough statistical references for adults, not goals. They ignore age, frame, muscle mass and health status. Ask a doctor or registered dietitian before setting any weight target.
How to use the ideal weight calculator
- Choose Metric (cm, kg) or Imperial (ft, in, lb). A height you have already typed is converted when you switch.
- Select your Sex (Male or Female). The published formulas use different constants for men and women.
- Enter your Height in centimetres, or in feet and inches. A decimal comma or point both work.
- Read the table: each Formula is shown with its Equation and the Reference weight it gives for your height. Above the table you see the Range of the four formulas and the Healthy BMI range (18.5–24.9) at your height.
- Clear empties the height fields.
Everything is calculated in your browser as you type. Nothing is sent anywhere.
The four formulas compared
“Ideal body weight” (IBW) equations were not designed to tell anyone what they should weigh. Most were created to estimate drug doses and kidney function in hospital patients. All of them start from a base weight at 5 feet (152.4 cm) and add a fixed amount per inch above that height:
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 kg + 2.3 kg per inch | 45.5 kg + 2.3 kg per inch |
| Robinson (1983) | 52 kg + 1.9 kg per inch | 49 kg + 1.7 kg per inch |
| Miller (1983) | 56.2 kg + 1.41 kg per inch | 53.1 kg + 1.36 kg per inch |
| Hamwi (1964) | 106 lb + 6 lb per inch | 100 lb + 5 lb per inch |
Worked example: a man who is 5 ft 10 in (177.8 cm) tall is 10 inches above 5 feet. Devine gives 50 + 2.3 × 10 = 73.0 kg, Robinson gives 71.0 kg, Miller gives 70.3 kg, and Hamwi gives 106 + 6 × 10 = 166 lb (75.3 kg). The spread of about 5 kg between formulas that all claim to be “ideal” is the clearest sign that these are rough references.
Hamwi’s rule was published in pounds, so this tool keeps his original pound values and converts them exactly (1 lb = 0.45359237 kg). The other three are applied in kilograms as published.
Comparison with the healthy BMI range
The tool also shows the weights that correspond to a body mass index of 18.5 to 24.9 at your height, the “normal weight” band of the World Health Organization. This range is wide on purpose: for a height of 170 cm it runs from about 53.5 to 72 kg. The single numbers from the IBW formulas usually fall inside it, which shows that many different weights are compatible with good health.
Limitations
- The formulas only use height and sex. They ignore age, frame size, muscle mass, fat distribution, ethnicity and medical history.
- They were derived for heights of 5 feet and above. Below 152.4 cm the tool warns that it is extrapolating a straight line, and it refuses heights outside 140–220 cm.
- They apply to adults, not to children, teenagers or pregnant people.
- None of them was validated as a health target. A lower weight is not automatically better.
Treat the results as a talking point, not a goal. If you are thinking about losing or gaining weight, talk to a doctor or a registered dietitian first. They can take your history into account and help you set safe, realistic steps.
Frequently asked questions
Which ideal weight formula is the most accurate?
None is “accurate” for an individual. Devine is the most used in clinical practice (for example in drug dosing), while Robinson and Miller were later attempts to fit weight tables better. Comparing them shows the uncertainty rather than a single truth.
Why do the formulas give different results?
They were fitted to different data sets and assumptions, decades ago. Their slopes differ (from 1.36 to about 2.7 kg per inch), so the gap between them grows as you move away from 5 feet.
Should I try to reach my ideal weight?
Not on the basis of these numbers alone. They are statistical references. A health professional can tell you whether your current weight is a concern, using measurements such as waist circumference, blood pressure and blood tests.
Does this calculator work for athletes?
Poorly. Muscular people often weigh more than any of these formulas suggest while being very lean, so the result says little about their health.
Why is the BMI range so much wider than the formulas?
BMI 18.5–24.9 is a band that reflects the range of weights associated with lower health risk in large populations. The formulas each give one point estimate, which suggests a precision they do not have.
Related tools
- BMI Calculator Calculate your adult body mass index in metric or imperial units, see the WHO BMI category and the weight range for a BMI of 18.5 to 24.9.
- Body Fat Calculator Estimate your body fat percentage from height, neck, waist and hip measurements with the US Navy formula, in centimetres or inches.
- BMR Calculator Estimate your basal metabolic rate with the Mifflin-St Jeor and revised Harris-Benedict equations, in metric or imperial units, with every step shown.