Health & Fitness
Ideal Weight Calculator
Four accepted formulas, shown side by side — because they disagree, and a single number would imply a precision that does not exist.
Ideal Weight Calculator
About the Ideal Weight Calculator
There is no single ideal weight, and this calculator refuses to pretend otherwise. It shows four accepted formulas side by side — Devine, Robinson, Miller and Hamwi — along with the healthy BMI range for your height.
They disagree, sometimes by several kilograms, because each was derived from different data for a different purpose. Showing one number would imply a precision that does not exist. Showing four makes the honest point: what you get is a range to orient yourself with, not a target to hit.
All four formulas are anchored at 5 feet and become unreliable below that height, which the page flags when it applies. None of them account for muscle, frame size or body composition.
How to use the Ideal Weight Calculator
- Choose your sex — every formula uses different constants for men and women.
- Pick metric or imperial units.
- Enter your height.
- Select Calculate ideal weight.
- Compare all four results and the healthy BMI range — treat the spread between them as the real answer.
The four IBW formulas: Devine, Robinson, Miller and Hamwi
Each IBW formula takes the same shape: a base weight at 5 feet, plus a fixed amount for every inch above it. Doctors use the Devine version most; the Hamwi formula is the quick rule many dietitians learn first.
Devine (1974) : men 50 + 2.3×(in−60) women 45.5 + 2.3×(in−60)
Robinson (1983): men 52 + 1.9×(in−60) women 49 + 1.7×(in−60)
Miller (1983) : men 56.2 + 1.41×(in−60) women 53.1 + 1.36×(in−60)
Hamwi (1964) : men 48 + 2.7×(in−60) women 45.5 + 2.2×(in−60)
Results in kilograms; "in" is height in inches.
Worked example
A man 1.80 m tall — 70.9 inches, so 10.9 inches above 5 feet.
Devine: 50 + 2.3×10.87 = 75.0 kg. Robinson: 52 + 1.9×10.87 = 72.6 kg.
Miller: 56.2 + 1.41×10.87 = 71.5 kg. Hamwi: 48 + 2.7×10.87 = 77.3 kg.
A 5.8 kg spread — and the healthy BMI range is 59.9 to 80.7 kg, wider still
Why they disagree
Because none of them were built to answer the question people now use them for.
- Devine (1974) was written for drug dosing, not health. Several medications are dosed on lean mass, and Devine was a convenient estimate of it. It remains the clinical standard for that job.
- Hamwi (1964) was a quick bedside rule for dietitians estimating nutritional needs.
- Robinson (1983) and Miller (1983) were revisions fitted to newer measured data, which is why they generally return lower figures at greater heights.
Each is internally consistent and none is wrong. They simply answer different questions, so the spread between them is information rather than error.
| Height | Devine | Robinson | Miller | Hamwi | Healthy BMI range |
|---|---|---|---|---|---|
| 1.60 m (men) | 56.9 | 57.7 | 60.4 | 56.1 | 47.4 – 63.7 |
| 1.70 m (men) | 65.9 | 65.2 | 66.0 | 66.7 | 53.5 – 72.0 |
| 1.80 m (men) | 75.0 | 72.6 | 71.5 | 77.3 | 59.9 – 80.7 |
| 1.60 m (women) | 52.4 | 54.1 | 57.2 | 52.1 | 47.4 – 63.7 |
| 1.70 m (women) | 61.4 | 60.8 | 62.5 | 60.7 | 53.5 – 72.0 |
Notice how the healthy BMI range brackets all four formulas at every height, and is considerably wider. That width is the more honest signal.
Adjusted body weight formula
Clinicians sometimes use adjusted body weight for patients well above their ideal weight, because neither actual nor ideal weight suits certain drug calculations:
AdjBW = IBW + 0.4 × (actual weight − IBW)
Devine IBW is normally the input. The 0.4 factor reflects that adipose tissue is metabolically active, but less so than lean tissue.
This is a clinical dosing tool. It is included here because people meet the term and want to know what it means, not as something to act on.
What these formulas cannot see
- Muscle. A heavily-built athlete will sit well above every formula while being perfectly healthy.
- Frame size. Wrist and shoulder width vary substantially between people of the same height.
- Age. Body composition shifts across decades; the formulas do not move.
- Where fat sits. Waist measurement carries information none of these capture.
For a composition estimate, use the body fat calculator. For the standard classification, the BMI calculator shows your healthy range directly.
This is a screening tool, not a diagnosis. It cannot see your muscle mass, bone density, medical history or family background, and it does not replace an examination. If you are concerned about your weight or health, speak to a doctor who can assess you properly.
Ideal weight chart by height in kg and lb (Devine formula)
The Devine formula is the one doctors and pharmacists use most. Here it is for common heights:
| Height | Men | Women |
|---|---|---|
| 5'0" (152 cm) | 50.0 kg (110 lb) | 45.5 kg (100 lb) |
| 5'2" (157 cm) | 54.6 kg (120 lb) | 50.1 kg (110 lb) |
| 5'4" (163 cm) | 59.2 kg (131 lb) | 54.7 kg (121 lb) |
| 5'6" (168 cm) | 63.8 kg (141 lb) | 59.3 kg (131 lb) |
| 5'8" (173 cm) | 68.4 kg (151 lb) | 63.9 kg (141 lb) |
| 5'10" (178 cm) | 73.0 kg (161 lb) | 68.5 kg (151 lb) |
| 6'0" (183 cm) | 77.6 kg (171 lb) | 73.1 kg (161 lb) |
| 6'2" (188 cm) | 82.2 kg (181 lb) | 77.7 kg (171 lb) |
So the ideal body weight for a 6-foot man is about 77.6 kg (171 lb) on Devine. The other formulas give slightly different answers, which is why the calculator shows all four.
Ideal weight vs healthy weight range
An "ideal weight" is a single point. A healthy weight is a range. For most people, a BMI of 18.5–24.9 is the more useful target, because it allows for different builds. Check your range with the BMI calculator, and track body fat with the body fat calculator.
Other ways to use this calculator
- Ideal body weight by height — the Devine chart above shows weight according to height.
- Ideal weight for men and ideal weight for women — every formula has separate figures for each sex.
- Robinson formula — one of the four formulas compared in the results.
- Healthy weight for height — compare with the BMI range, which is wider than any single formula.
Frequently asked questions
For general orientation, none of them alone — read the range they produce together, and note that the healthy BMI range is wider still. If you need a figure for a specific purpose, Devine is the clinical standard for drug dosing, Hamwi is a quick dietetic rule, and Robinson and Miller are later revisions fitted to newer data. That is exactly why this page shows all four rather than picking one.
Because each was derived from different data for a different purpose. Devine (1974) was written for drug dosing, Hamwi (1964) as a bedside dietetic rule, and Robinson and Miller (both 1983) as revisions against newer measurements. At 1.80 m they span about 5.8 kg. None is wrong — the spread tells you the concept itself is approximate.
No. None of these formulas can see body composition; they take height and sex and nothing else. A muscular person will sit above all four while carrying little fat, and someone with low muscle mass may sit within them while carrying a lot. If body composition is what you actually want to know, a body fat estimate or a waist measurement is a far better tool.
Because they were designed as simple bedside rules: take a base weight at 5 feet and add a fixed amount per inch above it. That linear shape is easy to do in your head, which mattered in 1964 and 1974. The consequence is that all four become unreliable below 5 feet, and the calculator flags this when your height falls under that anchor.
About 77.6 kg (171 lb) on the Devine formula. The Robinson, Miller and Hamwi formulas give nearby values, and a healthy BMI range for 6 feet is roughly 62 to 83 kg (136 to 184 lb).
Sources and further reading
- Devine BJ (1974) — Gentamicin therapy, Drug Intelligence & Clinical Pharmacy — the origin of the Devine formula as a drug-dosing estimate
- NHLBI — Assessing your weight and health risk — healthy weight ranges and waist circumference
- World Health Organization — Obesity and overweight — the 18.5–24.9 healthy BMI range shown alongside
- NHS — Healthy weight — practical guidance on target weight