Ideal Weight Calculator
Compare four established clinical formulas for ideal body weight, plus the healthy BMI range for your height.
Compare four established clinical formulas for ideal body weight, plus the healthy BMI range for your height.
Ideal Body Weight (IBW) is a clinical estimate of the healthiest weight for a given height. It was originally developed for use in medical settings, particularly for calculating drug dosages, assessing nutritional status, and determining healthy weight ranges. Today, IBW formulas are used by healthcare providers, dietitians, and fitness professionals as one of several tools for evaluating body composition.
It is important to understand that "ideal" weight is not a single number but rather a range that depends on your body composition, frame size, age, sex, and health goals. The formulas below provide statistical estimates based on population data, not personalized prescriptions.
Developed by Dr. B.J. Devine for calculating drug dosages, the Devine formula is the most widely used IBW equation in clinical medicine. It was derived from a study of height-weight relationships in a working population.
Male: 50.0 kg + 2.3 kg per inch over 5 feet
Female: 45.5 kg + 2.3 kg per inch over 5 feet
The Devine formula is used in hospital settings for calculating tidal volume in mechanical ventilation, drug dosages (particularly for medications that distribute primarily in lean tissue), and nutritional assessment. It tends to produce values in the middle of the range compared to other formulas.
Dr. J.D. Robinson revised the Devine formula in 1983 to better reflect contemporary body compositions. The Robinson formula generally produces slightly lower values than Devine, particularly for taller individuals.
Male: 52.0 kg + 1.9 kg per inch over 5 feet
Female: 49.0 kg + 1.7 kg per inch over 5 feet
The Robinson formula was developed by analyzing data from a broader population sample and is sometimes preferred in research settings where a more conservative IBW estimate is desired.
Dr. D.R. Miller published his formula in the same year as Robinson, but with higher base weights and per-inch additions. The Miller formula produces the highest IBW estimates among the four and may be more appropriate for larger-framed individuals.
Male: 56.2 kg + 1.41 kg per inch over 5 feet
Female: 53.1 kg + 1.36 kg per inch over 5 feet
The Miller formula was derived from life insurance data and aims to represent the weight associated with the lowest mortality risk. It tends to give values that correspond to a BMI of approximately 24-26.
The Hamwi formula is the oldest of the four, developed by Dr. G.J. Hamwi in 1964 for clinical nutrition assessment. Despite its age, it remains widely used in dietetic practice.
Male: 48.0 kg + 2.7 kg per inch over 5 feet
Female: 45.5 kg + 2.2 kg per inch over 5 feet
The Hamwi formula uses the highest per-inch increment for males, making it produce relatively high estimates for tall men. It was originally designed as a quick bedside tool for dietitians to assess whether patients were at a healthy weight.
In addition to the four IBW formulas, the healthy BMI range provides a weight interval based on the WHO's healthy BMI classification (18.5-24.9 kg/m2). For your height, this translates to:
Lower bound: 18.5 x height(m)2
Upper bound: 24.9 x height(m)2
The BMI range is broader than most IBW formulas because it includes the full spectrum of weights considered healthy by WHO standards. IBW formulas typically correspond to a BMI of 22-26, which is near the middle or slightly above the center of the healthy range.
| Context | Recommended Formula | Reason |
|---|---|---|
| Drug dosing | Devine | Most widely validated for pharmacokinetic calculations |
| Clinical nutrition | Hamwi or Devine | Standard in dietetic practice |
| Research | Robinson | Conservative estimate; good for population studies |
| Fitness goals | Average of all four | Provides a balanced target range |
| Insurance assessment | Miller | Derived from mortality data |
| General health | Healthy BMI range | Most inclusive; accounts for body frame variation |
All IBW formulas share a fundamental limitation: they use only height and sex as inputs, ignoring body composition, frame size, age, and ethnicity. This means:
Ideal body weight formulas are useful reference points but should never be the sole determinant of your health or weight goals. Use the average of the four formulas as a starting point, then factor in your body composition (body fat percentage), waist circumference, fitness level, and how you feel. For a more personalized assessment, combine IBW with BMI, body fat percentage, and lean body mass calculations.
Ideal body weight (IBW) is an estimate of the healthiest weight for a given height, based on population data and clinical outcomes. Multiple formulas exist because 'ideal' depends on the context: drug dosing, life insurance, clinical assessment, or fitness goals. No single formula is universally 'correct'; they provide a range that represents statistically healthy weights for your height.
The Devine formula (1974) is the most widely used in clinical settings, particularly for drug dosing calculations. The Robinson formula (1983) was developed as an improvement on Devine and tends to give slightly lower values. The Miller formula (1983) gives the highest estimates and may be more appropriate for larger-framed individuals. The Hamwi formula (1964) is the oldest and was originally designed for nutrition assessment. For most purposes, averaging the four provides a reasonable target range.
Not exactly. Ideal body weight formulas give a single number, while a healthy BMI range (18.5-24.9) translates to a weight range for your height. The IBW formulas generally correspond to a BMI of approximately 22-26, which falls within or slightly above the WHO healthy range. For a more individualized target, consider the healthy BMI range alongside IBW formulas, and factor in your body composition, age, and frame size.
Each formula was developed for different populations and purposes. Devine (1974) was created for drug dosing and is based on height alone. Robinson (1983) revised Devine to better match contemporary populations. Miller (1983) was derived from insurance data. Hamwi (1964) was designed for clinical nutrition assessment. They differ because 'ideal' weight varies by context, population era, and the health outcomes being optimized.
Ideal body weight formulas provide a useful reference point but should not be the sole determinant of your weight goal. Consider your body composition (muscle vs. fat), bone density, age, and overall health. A muscular individual may be healthiest above their calculated IBW. Conversely, someone with low muscle mass might benefit from body recomposition at their current weight. Use IBW as one data point alongside body fat percentage, waist circumference, and how you feel.
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