Where these formulas came from
The ideal body weight formulas were not designed as health targets. The Devine formula, published in 1974, was created to standardize medication dosing — particularly for drugs where dose depends on lean mass rather than total weight. The Robinson, Miller, and Hamwi variants are refinements from a similar clinical tradition.
All four share a structure: a base weight at five feet of height, plus a fixed increment for each additional inch. That simplicity is exactly why they remain useful for dosing and limited as personal goals — they encode nothing about frame size, muscle mass, age, or body composition.
| Formula | Men | Women | Origin |
|---|---|---|---|
| Hamwi (1964) | 48.0 + 2.7 per inch | 45.5 + 2.2 per inch | Quick clinical estimate; ±10% for small or large frame |
| Devine (1974) | 50.0 + 2.3 per inch | 45.5 + 2.3 per inch | Drug dosing; the most widely cited |
| Robinson (1983) | 52.0 + 1.9 per inch | 49.0 + 1.7 per inch | Modification of Devine |
| Miller (1983) | 56.2 + 1.41 per inch | 53.1 + 1.36 per inch | Modification of Devine; flattest slope |
Why a range beats a single number
The healthy BMI range of 18.5 to 24.9 spans a surprisingly wide band of weights. At 5 feet 10 inches, it runs from roughly 129 to 174 pounds — a 45-pound span, all of it consistent with a healthy BMI. Where you fall within it depends on your build and how much muscle you carry.
Muscle mass matters most in interpreting the result. A well-trained person can weigh substantially more than every formula suggests while carrying low body fat and being in excellent health. If your weight exceeds the formulas but your body fat percentage and blood work are good, the formulas are the thing that is wrong.
| Height | Pounds | Kilograms |
|---|---|---|
| 4′10″ (147 cm) | 89 – 119 lb | 40.2 – 54.0 kg |
| 5′0″ (152 cm) | 95 – 127 lb | 43.0 – 57.8 kg |
| 5′2″ (157 cm) | 101 – 136 lb | 45.9 – 61.8 kg |
| 5′4″ (163 cm) | 108 – 145 lb | 48.9 – 65.8 kg |
| 5′6″ (168 cm) | 115 – 154 lb | 52.0 – 70.0 kg |
| 5′8″ (173 cm) | 122 – 164 lb | 55.2 – 74.3 kg |
| 5′10″ (178 cm) | 129 – 174 lb | 58.5 – 78.7 kg |
| 6′0″ (183 cm) | 136 – 184 lb | 61.9 – 83.3 kg |
| 6′2″ (188 cm) | 144 – 194 lb | 65.4 – 88.0 kg |
| 6′4″ (193 cm) | 152 – 205 lb | 68.9 – 92.8 kg |
Adjusting for frame size
The Hamwi method is the only one of the four that formally accounts for build: subtract 10% for a small frame or add 10% for a large one. Frame is judged from wrist circumference relative to height, using the bands below. The calculator applies the adjustment to the Hamwi figure when you select a small or large frame; the other formulas have no such provision and are shown unadjusted.
| Height | Small frame | Medium frame | Large frame |
|---|---|---|---|
| Women under 5′2″ | wrist under 5.5″ | 5.5″ – 5.75″ | over 5.75″ |
| Women 5′2″ to 5′5″ | under 6″ | 6″ – 6.25″ | over 6.25″ |
| Women over 5′5″ | under 6.25″ | 6.25″ – 6.5″ | over 6.5″ |
| Men over 5′5″ | 5.5″ – 6.5″ | 6.5″ – 7.5″ | over 7.5″ |
Better questions to ask
Rather than targeting a specific weight, most people get more from asking whether their waist circumference is in a healthy range, whether their body fat percentage is reasonable for their sex and age, whether their blood pressure and blood work look good, and whether they are physically capable of what they want to do.
There is also good evidence that health behaviours improve outcomes largely independently of weight change. Regular activity, adequate sleep, and better diet quality reduce cardiovascular and metabolic risk whether or not the scale moves — which makes them a more reliable target than a number derived from a dosing formula.