“Ideal body weight” formulas turn your height into a single target number. They date from the 1960s to the 1980s, and although they were never meant to define the perfect weight for an individual, they are still used in clinical dosing and are a common reference point. This calculator runs the four best-known versions side by side and adds the healthy BMI range, which is the measure public-health agencies use today.
How to use the ideal weight calculator
- Choose US or Metric units.
- Select sex — each formula has separate male and female constants.
- Enter your height.
- Compare the four formula results, the range they span, and the healthy BMI band shown in the chart.
Ideal weight formulas
Every formula has the same shape: a base weight at 5 feet (60 inches) plus a fixed amount for each inch above it.
| Formula | Men (kg) | Women (kg) |
|---|---|---|
| Devine (1974) | 50 + 2.3 per inch | 45.5 + 2.3 per inch |
| Robinson (1983) | 52 + 1.9 per inch | 49 + 1.7 per inch |
| Miller (1983) | 56.2 + 1.41 per inch | 53.1 + 1.36 per inch |
| Hamwi (1964) | 48 + 2.7 per inch | 45.5 + 2.2 per inch |
Hamwi’s version is often quoted in pounds: 106 lb plus 6 lb per inch for men and 100 lb plus 5 lb per inch for women.
Worked example
For a man who is 5 ft 10 in, height is 10 inches over 5 feet:
Devine: 50 + 2.3 × 10 = 73.0 kg (160.9 lb)
Robinson: 52 + 1.9 × 10 = 71.0 kg (156.5 lb)
Miller: 56.2 + 1.41 × 10 = 70.3 kg (155.0 lb)
Hamwi: 48 + 2.7 × 10 = 75.0 kg (165.3 lb)
The formulas span 155.0 – 165.3 lb, while a BMI of 18.5 to 24.9 at the same height covers 128.9 – 173.5 lb.
For a woman who is 5 ft 4 in, the four formulas give 119.7 lb (Hamwi), 120.6 lb (Devine), 123.0 lb (Robinson) and 129.1 lb (Miller), against a healthy BMI range of 107.8 – 145.1 lb.
Where these formulas came from
George Hamwi published his quick rule in 1964 as a dietary planning aid for people with diabetes. Ben Devine proposed his equation in 1974 to calculate doses of the antibiotic gentamicin, and it spread through pharmacy practice from there. In 1983, J. D. Robinson and D. R. Miller each refitted the idea to the Metropolitan Life height-weight tables, which is why their increments per inch are smaller. None of the four accounts for age, muscle mass or body frame, and all assume an adult of at least 5 feet.
Ideal weight versus healthy BMI
The formulas return one number, while the BMI method returns a band about 40 pounds wide at average heights. The formula results usually land in the upper half of that band for men and near its middle for women. A weight outside the formula values but inside the BMI range is not a warning sign by itself; body composition, waist size, fitness and medical history say far more about health than any one target. For a composition-based view, try the body fat calculator, and for the energy side of weight, the calorie calculator.
Adjusting for frame size
Hamwi suggested a 10% allowance in each direction: subtract it for a small frame and add it for a large one. For the 5 ft 10 in man above, his Hamwi value of 165 lb would become roughly 149 lb (small frame) or 182 lb (large frame).
These formulas are informational only and are not medical advice. They are not personal weight goals; a healthcare professional can help you decide what a healthy weight means for you.
Frequently asked questions
Which ideal weight formula is the most accurate?
None is accurate in the sense of predicting the healthiest weight for you. Devine's equation is the most widely used in hospitals because it became the standard for drug dosing; Robinson and Miller were later fitted to population data. The spread between formulas is a reminder that ideal weight is a range.
Why do the formulas give different answers?
Each starts from a different base weight at 5 feet and adds a different amount per inch, because each was derived from different data or for a different purpose. The gap is usually small near average heights and widens for very tall people, where Hamwi and Devine climb faster than Miller.
Does body frame size change ideal weight?
Hamwi's original rule suggested subtracting about 10% for a small frame and adding 10% for a large frame. Frame size is usually judged from wrist circumference or elbow breadth. The calculator shows medium-frame values; you can apply the 10% adjustment yourself.
Is ideal body weight still used in medicine?
Yes. Clinicians use it, or the closely related predicted body weight, to dose some medications and to set ventilator volumes, because those depend more on lean body size than on total weight. That clinical use is quite different from choosing a personal goal weight.