Find your ideal body weight using four scientific formulas. Enter your height and sex — get results in both kg and lbs, plus a comparison of all four methods.
| Formula | kg | lbs |
|---|---|---|
| Devine1974 | — | — |
| Robinson1983 | — | — |
| Miller1983 | — | — |
| Hamwiclassic | — | — |
| Average | — | — |
The most widely used formula in medicine. Originally developed to determine drug dosing. Male: 50 + 2.3 × (height_in − 60). Female: 45.5 + 2.3 × (height_in − 60).
Derived from life insurance actuarial tables. Slightly higher than Devine for men, lower for women. Male: 52 + 1.9 × (height_in − 60). Female: 49 + 1.7 × (height_in − 60).
Produces the highest IBW of the four formulas, making it more appropriate for taller individuals and athletes. Male: 56.2 + 1.41 × (height_in − 60). Female: 53.1 + 1.36 × (height_in − 60).
Popular with clinical dietitians and nurses. Uses a simple rule-of-thumb approach. Male: 48 + 2.7 × (height_in − 60). Female: 45.4 + 2.2 × (height_in − 60).
Ideal body weight (IBW) is a reference weight calculated from a person's height and biological sex. It represents the weight at which research suggests a person is at the lowest risk of weight-related health complications — including type 2 diabetes, cardiovascular disease, hypertension, and certain cancers. Unlike BMI, which gives a range, IBW formulas produce a specific target weight, making them useful as a concrete goal for weight management programs.
The concept of ideal body weight dates back to the early 20th century, when life insurance actuaries began compiling data on which body weights correlated with the longest life expectancy. Over time, this actuarial data was refined into clinical formulas, the most enduring of which — Devine, Robinson, Miller, and Hamwi — are still used today in hospital settings, fitness planning, and nutritional counseling.
In clinical settings, ideal body weight is used primarily for two purposes. First, it informs drug dosing calculations — particularly for medications where toxicity is a concern, such as aminoglycosides, chemotherapy agents, and anesthetics. Using actual body weight for obese patients would result in overdosing, so physicians use IBW or adjusted body weight instead. Second, IBW serves as a target in obesity treatment programs, helping clinicians set realistic intermediate weight-loss goals for patients.
Outside of hospitals, personal trainers, nutritionists, and app users use IBW to gauge progress and set realistic targets. It is important to remember, however, that these formulas were derived from population data collected decades ago, primarily from Western populations. They are reference points, not diagnostic criteria.
There is an important distinction between ideal weight (a single number from a formula) and healthy weight range (derived from BMI 18.5–24.9). For most adults of average height (165–180 cm), the formula-calculated IBW tends to fall near the middle of the BMI-healthy range — which is reassuring about their validity. However, for very short or very tall individuals, the two measures can diverge significantly.
For a 160 cm woman, for example, the Devine formula gives an IBW of approximately 50 kg, while the BMI-healthy range is 47.4–63.7 kg. The IBW sits toward the lower end of the healthy range, which may not be realistic or desirable for all body types. This is why most experts recommend using the BMI healthy range as a more flexible and inclusive target.
Yes — and the formulas capture this with a linear relationship: for every inch of height above 5 feet (60 inches), the IBW increases by a fixed amount per formula. Devine adds 2.3 kg per inch, Robinson adds 1.9 kg (men) or 1.7 kg (women), Miller adds 1.41 kg (men) or 1.36 kg (women), and Hamwi adds 2.7 kg (men) or 2.2 kg (women).
This means the formulas were designed with a reference baseline of exactly 5 feet (152.4 cm). If you are shorter than 5 feet, the formula subtracts from the base weight. All four formulas assume height is the dominant predictor of ideal weight — age, frame size, and fitness level are not factored in, which is both a strength (simplicity) and a limitation (imprecision) of the approach.
Some older ideal weight charts included an adjustment for body frame size — classified as small, medium, or large based on wrist circumference or elbow breadth. A large-framed person, for instance, might have a higher IBW than a small-framed person of the same height. While these adjustments are not included in the modern formulas used by this calculator, they can be a useful mental model: if you naturally carry more bone and muscle than average, being slightly above your formula IBW is physiologically normal.
Body composition — the ratio of fat to lean mass — is ultimately a more informative metric than either IBW or BMI. A DEXA scan (dual-energy X-ray absorptiometry) provides the most accurate measurement of body fat percentage, lean mass, and bone density. For practical purposes, body fat percentage targets are: 10–20% for men (athletic 6–17%), and 18–28% for women (athletic 14–24%).
Reaching your ideal weight is a long-term process best approached with sustainable habits rather than rapid interventions. Here are the evidence-based principles that consistently produce results:
If your current weight is more than 20% above or below your ideal weight, or if you have underlying health conditions such as diabetes, cardiovascular disease, or thyroid disorders, consult a physician or registered dietitian before starting a weight-change program. Rapid weight loss (more than 1 kg per week) can deplete muscle mass, cause nutrient deficiencies, and — in extreme cases — lead to gallstones or cardiac complications. A professional can help you set a safe rate of loss and monitor biomarkers throughout the process.
Log your weight, build daily exercise habits, track water intake, and stay consistent on your way to your ideal weight — all in one free app.
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