Free Ideal Weight Calculator

Compare your ideal weight across 4 scientific formulas — Hamwi, Devine, Miller, and Robinson — plus your healthy BMI weight range. Supports Imperial and Metric units.

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Enter your height to see your ideal weight across 4 formulas.

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What Is Ideal Body Weight?

Ideal body weight (IBW) is a weight range associated with good health and reduced risk of weight-related diseases for a given height and sex. It is not a single magic number but rather a range, and it should be understood as one reference point among many — not a definitive target everyone must achieve.

Clinicians use IBW formulas to guide medication dosing, nutritional assessments, and health screenings. For the general public, IBW estimates provide a useful starting point for understanding healthy weight goals. The most important factor is long-term health, energy levels, and sustainable habits — not a specific number on the scale.

The Four Ideal Weight Formulas Explained

Our calculator uses four widely cited formulas, each developed independently by researchers studying different populations. All formulas base their calculations on height and sex, and produce results in kilograms which can be converted to pounds.

Hamwi Formula (1964): Developed by Dr. G.J. Hamwi for clinical use. For men: 48 kg for 5 feet, plus 2.7 kg per inch above 5 feet. For women: 45.5 kg plus 2.2 kg per inch above 5 feet. The Hamwi formula is still commonly used in dietetic practice.

Devine Formula (1974): Originally created for medication dosing calculations by Dr. B.J. Devine. For men: 50 kg plus 2.3 kg per inch above 5 feet. For women: 45.5 kg plus 2.3 kg per inch above 5 feet. It is the most widely referenced IBW formula in medical literature.

Robinson Formula (1983): A revision by Robinson et al. intended to improve on the Devine formula. For men: 52 kg plus 1.9 kg per inch above 5 feet. For women: 49 kg plus 1.7 kg per inch above 5 feet. It generally predicts slightly higher IBW than Devine.

Miller Formula (1983): Another revision developed in the same era. For men: 56.2 kg plus 1.41 kg per inch above 5 feet. For women: 53.1 kg plus 1.36 kg per inch above 5 feet. Miller's formula tends to yield the highest IBW estimates of the four.

Our calculator also shows the Healthy BMI Range (18.5–24.9) weight for your height, calculated directly from the BMI formula. This provides an independent cross-reference based on population health data.

Which Formula Should I Use?

There is no single "best" formula — each was developed for different contexts and populations. Looking at the average across all four formulas gives a reasonable central estimate. The healthy BMI range weight is particularly useful as it is derived from large epidemiological studies linking BMI to health outcomes. If your weight is within the range shown by most formulas, that is a healthy sign.

Frequently Asked Questions

No single formula is definitively most accurate for everyone. The Devine formula is the most widely referenced in clinical settings. The healthy BMI range (18.5–24.9) is derived from the largest population-level health data. Looking at the average of all four formulas plus the BMI range gives the most balanced picture of your healthy weight target.

No — all four IBW formulas consider only height and sex. They do not distinguish between muscle and fat mass. A heavily muscular person may weigh more than their "ideal" weight but still be very healthy. Conversely, someone at their "ideal" weight could have poor muscle tone and high body fat. IBW is a useful reference, not a comprehensive health measure.

Each formula was developed by different researchers studying different populations in different decades. They used varying statistical methodologies and had different clinical applications in mind. For example, the Devine formula was created for drug dosing; the Hamwi formula for nutritional assessment. The variation between formulas reflects genuine scientific uncertainty about a single "ideal" weight.

Not exactly, but there is significant overlap. The healthy BMI range (18.5–24.9 kg/m²) gives a weight range at your height that is statistically associated with lower risk of chronic disease across large populations. The IBW formulas give a single point estimate. The BMI-derived range is arguably more evidence-based for the general population but still has the limitation of not accounting for body composition.

Being below your ideal weight (BMI under 18.5) may indicate insufficient nutrition, low muscle mass, or an underlying health condition. If unintentional weight loss has occurred, consult a doctor. For those who are naturally lean, it may simply reflect genetic body type. Gaining weight through structured strength training and a calorie surplus with adequate protein is the healthiest approach to reaching a higher weight.

Yes, these formulas do give lower ideal weights for women than men at the same height. This reflects biological differences: on average, women have smaller bone density and frame size, and carry a higher proportion of essential fat relative to muscle than men. These are population-level observations; individual variation is significant and body composition matters more than the number alone.

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