How to use it
- Choose metric or US units and your sex.
- Enter your height.
- Compare the four formula results and the healthy BMI weight range.
The formulas
All four take a base weight at 5 ft (60 in, 152.4 cm) and add a fixed amount for every inch above it:
| Formula | Men | Women |
|---|---|---|
| Hamwi (1964) | 48 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in |
| Devine (1974) | 50 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in |
| Robinson (1983) | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in |
| Miller (1983) | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
Hamwi originally published his rule in pounds (106 lb + 6 lb per inch for men, 100 lb + 5 lb per inch for women); the table shows the usual metric form. The healthy range is the weight that gives a BMI of 18.5 to 24.9: 18.5 × height² to 24.9 × height², height in metres.
Worked example
A man 175 cm tall is 68.9 in, so 8.9 in above 5 ft:
- Devine: 50 + 2.3 × 8.9 = 70.5 kg
- Robinson: 52 + 1.9 × 8.9 = 68.9 kg
- Miller: 56.2 + 1.41 × 8.9 = 68.7 kg
- Hamwi: 48 + 2.7 × 8.9 = 72.0 kg
- healthy BMI range: 18.5 × 1.75² = 56.7 kg to 24.9 × 1.75² = 76.3 kg
Why these are rough numbers
The formulas ignore frame size, muscle, age and where fat is carried, and were never validated as health targets. A weight anywhere in the healthy BMI band can be fine, and some people are healthy outside it. If you want a personal goal, a doctor or dietitian can help set one.