Ideal weight calculator — Devine, Robinson, Miller and Hamwi
Compare four clinical ideal body weight formulas against the healthy BMI range for your height, in kilograms or pounds, with the maths shown.
- Runs in your browser
- Nothing you enter is sent
- Free, no account
These equations were built from male and female reference groups — pick the one closest to your physiology.
5 ft 6.1 in
Only used to show how far you are from each estimate.
Applies the Hamwi ±10% frame allowance. Quick check: wrap your thumb and middle finger around the opposite wrist — overlapping suggests a small frame, not touching a large one.
These equations were designed for medication dosing and ventilator settings, not for setting a personal goal weight. There is no single correct weight for a given height.
All four side by side
Written for gentamicin dosing and still the standard in clinical pharmacy. The most widely quoted of the four.
A re-fit of the Devine data against the Metropolitan Life tables. Reads lower than Devine at tall heights.
The flattest gradient of the four: it adds least per inch, so it is the most generous for short people and the most conservative for tall ones.
The bedside rule dietitians learned: 106 lb for the first 5 ft plus 6 lb an inch for men, 100 lb plus 5 lb an inch for women. Allows ±10% for frame size.
On one scale
Green band = the healthy BMI range. D = Devine, R = Robinson, M = Miller, H = Hamwi.
The formula, with your numbers
- Height over 5 ft
- 66.1 in − 60 in = 6.1 in
- Devine
- 45.5 kg + (2.3 × 6.1 in over 5 ft) = 59.6 kg
- Robinson
- 49.0 kg + (1.7 × 6.1 in over 5 ft) = 59.4 kg
- Miller
- 53.1 kg + (1.36 × 6.1 in over 5 ft) = 61.5 kg
- Hamwi
- 45.5 kg + (2.2 × 6.1 in over 5 ft) = 59 kg
- Healthy BMI range
- 18.5 × 2.822 m² to 24.9 × 2.822 m² = 52.2 kg – 70.3 kg
Every formula uses the same shape: a base weight at 5 ft, plus a fixed amount per inch above it. They differ only in the base and the gradient.
What this means
The four formulas cluster between 59 kg and 61.5 kg, averaging 59.9 kg. The healthy BMI range for your height is wider: 52.2 kg to 70.3 kg. That width is the honest answer — a 52.2 kg and a 70.3 kg version of you can both be perfectly healthy.
At 68 kg you are 8.1 kg above it, with a BMI of 24.1. That is already inside the healthy BMI range.
None of these formulas know anything about muscle. A lifter can sit well above every line on this page and be leaner than someone sitting on it. Use the range as a sanity check, then judge progress with a tape measure and how your training is going.
How to use this calculator
- Choose metric or imperial and enter your height — that is the only required input.
- Add your current weight if you want to see how far you sit from each estimate and what your BMI is.
- Pick a frame size to apply the Hamwi ±10 percent allowance. If you are not sure, leave it on medium.
- Compare all four formulas against the healthy BMI band on the single scale — the spread is the point.
The four formulas
All four share the same structure: a base weight at 5 feet (152.4 cm), plus a fixed amount for every inch above that. They differ only in the base and the slope.
| Formula | Year | Men | Women |
|---|---|---|---|
| Hamwi | 1964 | 48.0 kg + 2.7 kg per inch over 5 ft | 45.5 kg + 2.2 kg per inch over 5 ft |
| Devine | 1974 | 50.0 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Robinson | 1983 | 52.0 kg + 1.9 kg per inch over 5 ft | 49.0 kg + 1.7 kg per inch over 5 ft |
| Miller | 1983 | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft |
Because the slopes differ, the formulas cross over. Miller has the highest base and the shallowest slope, so it reads highest for short people and lowest for tall ones. Hamwi is the opposite. At around 5 ft 8 in they all sit within a couple of kilograms of each other.
Where these formulas came from — and what they are for
None of them were designed to give you a personal goal. B. J. Devine published his in 1974 as a way of standardising gentamicin dosing, because dosing an antibiotic on total body weight over-doses people carrying a lot of fat — fat is poorly perfused and holds little of a water-soluble drug. Robinson and Miller later re-fitted the same Metropolitan Life insurance data. Hamwi's rule came from the 1964 American Diabetes Association guidance for diabetes meal planning.
Ideal body weight is still used every day in clinical practice, for:
- Weight-based drug dosing, particularly aminoglycoside antibiotics and chemotherapy
- Setting tidal volumes in mechanical ventilation (6–8 ml per kg of predicted body weight)
- Estimating baseline nutritional requirements in hospital
What they are not is a target. They contain no information about muscle, frame or body fat, and the underlying insurance data reflected mid-20th-century American populations.
Ideal weight at common heights
Average of the four formulas, alongside the healthy BMI range for comparison.
| Height | Men (average of 4) | Women (average of 4) | Healthy BMI range |
|---|---|---|---|
| 1.55 m · 5 ft 1 in | 53.5 kg | 48.7 kg | 44 – 60 kg |
| 1.60 m · 5 ft 3 in | 57.3 kg | 52.2 kg | 47 – 64 kg |
| 1.65 m · 5 ft 5 in | 61.1 kg | 55.8 kg | 50 – 68 kg |
| 1.70 m · 5 ft 7 in | 65.0 kg | 59.3 kg | 53 – 72 kg |
| 1.75 m · 5 ft 9 in | 68.8 kg | 62.8 kg | 57 – 76 kg |
| 1.80 m · 5 ft 11 in | 72.6 kg | 66.4 kg | 60 – 81 kg |
| 1.85 m · 6 ft 1 in | 76.5 kg | 69.9 kg | 63 – 85 kg |
| 1.90 m · 6 ft 3 in | 80.3 kg | 73.5 kg | 67 – 90 kg |
Two things stand out. The formulas cluster tightly — usually within 4 kg of each other — and they consistently sit in the lower half of the healthy BMI range. That is a feature of their insurance-table origins, not evidence that the upper half of the BMI range is unhealthy.
Frame size and why it matters
Skeletal frame genuinely varies. Two people of the same height can differ by several kilograms of bone and connective tissue before any consideration of muscle or fat. Hamwi's original rule allowed ±10 percent for large and small frames, which this calculator applies.
Two quick ways to estimate your frame:
- Wrist test. Wrap your thumb and middle finger around the opposite wrist. If they overlap, small frame; if they just touch, medium; if they do not meet, large.
- Wrist circumference against height. For a woman under 1.63 m, under 14 cm is small and over 16.5 cm is large. For a man over 1.65 m, under 16.5 cm is small and over 19 cm is large.
A more useful way to think about it
There is no single ideal weight, and chasing one is usually counterproductive. What the evidence supports is a healthy range plus a few markers that matter far more than the number on the scale:
- A waist under half your height
- Body fat inside the fitness or athletic bands for your sex
- Enough muscle to do what you want to do, now and at seventy
- Blood pressure, lipids and fasting glucose in range
- A weight you can hold without constant restriction
Someone at the top of the healthy BMI range who lifts and walks daily is in better shape than someone hitting a Devine number through chronic under-eating. Use the range above as a sanity check, then judge yourself on the things that actually respond to training and habits.
Questions
Is there really one ideal weight?
No. These formulas were written for drug dosing and ventilator settings, not for setting a personal goal. Treat the spread between them and the healthy BMI range as a sensible band, not a target to hit exactly.
Which formula is used in hospitals?
Devine (1974) is still the most common in clinical pharmacy for weight-based dosing. Robinson and Miller were later re-fits of the same data set, and Hamwi (1964) is the quick bedside rule dietitians learned.
Do the formulas work if I am under five feet tall?
Not well. All four are anchored at 5 ft (152.4 cm) and simply subtract per inch below that, which under-predicts. Below 5 ft, the healthy BMI range shown alongside is the more reliable guide.
How do I adjust for frame size?
The Hamwi rule allows plus or minus 10 percent for large or small frames, which this calculator shows as a range. A quick proxy: wrap thumb and middle finger around the opposite wrist — overlap suggests a small frame, no touch a large one.