Ideal Weight Calculator
See how much you should weigh for your height and sex. This calculator shows four classic ideal-weight formulas alongside your healthy BMI weight range.
Built and reviewed by Jesse · Last reviewed
Enter your height and sex to see your ideal weight estimates.
- Enter your height and sex. The classic formulas use height and sex to give a reference weight.
- Read the four estimates. Robinson, Miller, Devine, and Hamwi each give a slightly different target.
- Compare with your healthy BMI range. The calculator also shows the weight range for a BMI of 18.5-24.9 at your height.
Each classic formula defines a base weight at a height of 5 feet (152.4 cm) and adds a set amount for every inch above that. The four equations — Robinson, Miller, Devine, and Hamwi — differ in those numbers because each was derived from different data, which is why they produce a spread of results rather than a single figure.
Alongside the formulas, this calculator shows the weight range that corresponds to a healthy Body Mass Index (18.5–24.9) at your height. Most clinicians now favour this range over a single "ideal" number because it acknowledges that healthy bodies come in different shapes and sizes.
Because everything hangs off a per-inch increment, your height is the only input that matters and a sloppy measurement is expensive: recording your height 2 cm short moves the answers by 1.1 to 2.1 kg, depending on the formula. Measure once without shoes, heels against a wall, and reuse that figure.
Every one of these formulas knows your height and your sex, which means it has quietly assumed how much muscle, bone, and organ tissue you carry. That assumption is the whole ball game. Take two men at 178 cm: one lifts and carries about 68 kg of lean mass, the other does not and carries about 58 kg. Here is what each candidate target weight would require of them, if they arrived there with their lean mass intact:
| Reference weight | Target | Man A (lean 68 kg) | Man B (lean 58 kg) |
|---|---|---|---|
| Robinson (1983) | 71.1 kg | 4.4% | 18.4% |
| Miller (1983) | 70.4 kg | 3.4% | 17.6% |
| Devine (1974) | 73.2 kg | 7.1% | 20.8% |
| Hamwi (1964) | 75.2 kg | 9.6% | 22.9% |
| Average of the four | 72.5 kg | 6.2% | 20.0% |
| Top of the healthy BMI range | 78.9 kg | 13.8% | 26.5% |
Implied body fat is (target weight minus lean mass) divided by target weight. Nobody holds lean mass perfectly constant while losing weight, so the real figures land a little higher.
The same numbers mean opposite things. For man B, the four formulas land in the ordinary healthy range and the top of the BMI band is comfortably attainable. For man A they describe a physique-competition body: the average of the four would put him near single-digit body fat, which is not a weight to hold year round. He has not failed the formulas — the formulas were never told he existed.
Run the arithmetic the other way and it becomes useful. Pick the body fat you actually want, and your lean mass fixes the weight that goes with it: goal weight = lean mass / (1 − target body fat).
| Target body fat | Man A (lean 68 kg) | Man B (lean 58 kg) |
|---|---|---|
| 15% body fat | 80.0 kg (BMI 25.2) | 68.2 kg (BMI 21.5) |
| 20% body fat | 85.0 kg (BMI 26.8) | 72.5 kg (BMI 22.9) |
| 25% body fat | 90.7 kg (BMI 28.6) | 77.3 kg (BMI 24.4) |
BMI shown for the same weight, to see where each goal sits against the standard categories.
Note what happens to man A: a perfectly reasonable 20% body fat puts him above the healthy BMI band entirely. That is a known limit of BMI in muscular people rather than a health verdict — the guide to what BMI can and cannot see covers where the two measures part company.
The insurance-company height-weight tables that these equations were built to approximate did not publish one weight per height. They published three, for small, medium, and large frames, with frame size judged from a skeletal measurement such as elbow breadth. Frisancho's analysis of 21,752 adults in the NHANES I and II surveys set out reference weights by height, sex, and frame size for exactly this reason: at the same height, adults with broader frames sit at a higher reference weight.
Collapsing that into a single number is what makes these formulas convenient, and it is also what makes them blunt. The rule of thumb that accompanied the Hamwi method, the oldest of the four, was an allowance of roughly 10% either side of the reference weight for a small or large frame. Applied to the 178 cm average above, that turns a single 72.5 kg target into a band from 65.3 to 79.8 kg — a spread of 14.5 kg that a single number cannot show you.
You do not need calipers to use this. If your wrists, ankles, and shoulders are visibly broad or narrow for your height, read the formulas as the middle of a band rather than as a number, and let your ideal weight chart row be a starting point instead of a verdict.
- Choose metric or imperial units and select your sex.
- Enter your height.
- Compare the four formula estimates, their average, and the healthy BMI range.
- Use the range — not a single number — to set a realistic goal, then head to the body weight planner to turn that target into a daily calorie number and a timeline, or the calorie deficit calculator to compare different deficit sizes.
- Ignores body composition.The formulas use only height and sex, so a muscular person can read as "overweight" despite being lean. Check your BMI and, ideally, body fat percentage for a fuller picture.
- No frame-size adjustment. People with larger or smaller frames naturally carry more or less weight at the same height.
- Derived from older population data.These equations date from the 1960s–1980s and were built for clinical estimates, not as fitness goals. Devine's, the most widely used of the four, was published in 1974 as a way to scale a gentamicin dose.
- They disagree with each other, and with BMI. All four are linear in height while BMI is quadratic, so the body mass index each one implies drifts as height changes, and the four formulas hold women to a lower implied BMI than men. Our analysis of the four formulas measures that drift across the whole adult height range.
- Nothing below 5 feet. Each formula is defined as a base weight at 152.4 cm plus an increment for the inches above it, so there is nothing left to subtract below that height: every shorter height returns the same base weight. For adults under 5 feet, the healthy BMI range is the only one of these figures that still responds to your height.
Ideal body weight formulas (base at 152.4 cm / 5 ft, per inch above)
Robinson (1983): men 52 + 1.9/in; women 49 + 1.7/in
Miller (1983): men 56.2 + 1.41/in; women 53.1 + 1.36/in
Devine (1974): men 50 + 2.3/in; women 45.5 + 2.3/in
Hamwi (1964): men 48 + 2.7/in; women 45.5 + 2.2/in- in
- = inches of height above 5 feet (152.4 cm)
Results are in kilograms. These formulas predate BMI and give a single reference weight, so the healthy BMI range is usually the more practical target.
What is ideal body weight?
Ideal body weight (IBW) is an estimate of a healthy reference weight based on your height and sex. The classic formulas were originally developed in medicine — for example, to calculate drug dosages — and give a single target number. They're a useful starting point but not a precise health goal.
Which ideal weight formula is best?
There's no single 'best' formula — the Robinson, Miller, Devine, and Hamwi equations all give slightly different numbers because they were derived from different data. That's why this calculator shows all four plus their average. For most people, the healthy BMI range is a more meaningful target than any single formula.
Why show a healthy weight range instead of one number?
Because no single weight is right for everyone of a given height. A range based on a normal BMI (18.5–24.9) reflects that healthy people come in different builds. Where you fall within that range depends on your muscle mass, frame size, and personal goals.
Do these formulas account for muscle or body fat?
No. Ideal weight formulas use only height and sex, so they can't tell muscle from fat. A muscular athlete may weigh well above their 'ideal' number while carrying very little fat. If you're lean and strong, don't be alarmed by a high reading — body fat percentage is far more informative.
Should I aim for exactly my ideal weight?
Not necessarily. Use the number as a rough reference, not a strict target. Health depends on far more than weight — activity, diet quality, sleep, strength, and metabolic markers all matter. Aim for a weight where you feel strong, energetic, and can sustain your habits long term.
Does ideal weight change with age?
The formulas themselves don't adjust for age, but a slightly higher body weight in older adults is often associated with better outcomes. As always, the formulas are a starting point — individual circumstances matter more than a single equation.
What should my goal weight be if I lift weights?
Higher than these formulas suggest, usually. A reference weight assumes an average amount of muscle for your height, so a trained person hits it only by stripping fat to athletic levels. At 178 cm with 68 kg of lean mass, the average of the four formulas (72.5 kg) would mean roughly 6.2% body fat. Work from your lean mass instead of your height.
How do I set a goal weight from my body fat percentage?
Two steps. First, lean mass = current weight × (1 − current body fat). Then goal weight = lean mass ÷ (1 − target body fat). A 90 kg man at 25% body fat has 67.5 kg of lean mass, so a 15% target means 67.5 ÷ 0.85 = 79.4 kg. It assumes you keep your lean mass, which is roughly true with enough protein, resistance training, and a moderate deficit.
Does frame size change my ideal weight?
Yes, and the original clinical tables said so — they listed separate weights for small, medium, and large frames, judged from a skeletal measurement such as elbow breadth. The four formulas collapse that into one number. The traditional allowance was about 10% either side of the reference weight, which is a spread of several kilograms at most adult heights.
Why is my ideal weight lower than the top of my healthy BMI range?
Because the formulas aim near the middle of the healthy band rather than its edge. At 178 cm they average 72.5 kg while a BMI of 24.9 allows 78.9 kg — the whole upper half of the normal range sits above the 'ideal' figure. Nothing is wrong with being there.
How is this different from a BMI calculator?
A BMI calculator tells you which weight category you currently fall into. An ideal weight calculator works in reverse: it estimates what you might weigh at a healthy point for your height. They're complementary — use BMI to assess where you are, and ideal weight to set a rough goal.
References
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655 (Devine formula).
- Robinson JD, Lupkiewicz SM, Palenik L, et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm. 1983;40(6):1016-1019.
- Frisancho AR. New standards of weight and body composition by frame size and height for assessment of nutritional status of adults and the elderly. Am J Clin Nutr. 1984;40(4):808-819.
- World Health Organization. Body mass index (BMI) classification for adults.
FitCalcs calculators provide general estimates for healthy adults and are not medical advice.
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