This calculator is for education. It isn’t medical advice.
The formula
Each formula starts from a base weight at 5 ft (60 inches) and adds a fixed amount for every inch above that. Devine’s, for men:
is height in inches and the result is in kg.
| Formula | Men | Women |
|---|---|---|
| Hamwi (1964) | 48 + 2.7 per inch | 45.5 + 2.2 per inch |
| 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 |
Where it comes from
The history is surprising. In 1974, the pharmacist Ben Devine needed a way to dose the antibiotic gentamicin, which spreads through lean tissue rather than fat. He proposed a quick estimate of lean weight from height. His paper gave no data or derivation. The numbers appear to have been adapted from earlier rules of thumb, such as Hamwi’s 1964 formula for planning diabetic diets.
Despite that, Devine’s formula spread throughout hospital pharmacy. In 1983, Robinson and Miller each published new versions fitted to the Metropolitan Life Insurance height-weight tables, which were based on the weights associated with the lowest death rates among insured people. That’s why the four formulas disagree: they’re different fits to different, rather old, reference data.
A 2000 review by Pai and Paloucek traced this history and concluded the formulas are best treated as dosing tools, not health targets.
Worked example
A man 5 ft 10 in tall (70 inches, 178 cm), with Devine:
Robinson gives 71 kg, Miller 70.3 kg and Hamwi 75 kg.
Watch out for
- Not a goal weight. These formulas ignore frame size, muscle and body composition. For a general health check, BMI or waist-to-height ratio are better studied.
- Below 5 ft the formulas give unrealistic results, so the calculator doesn’t use them there.
- Clinical use. For drug dosing, follow your institution’s chosen formula.
Sources
- Pai, M. P. & Paloucek, F. P. (2000). The origin of the "ideal" body weight equations. Annals of Pharmacotherapy 34(9), 1066–1069.
- Devine, B. J. (1974). Gentamicin therapy. Drug Intelligence and Clinical Pharmacy 8, 650–655.
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