Ideal Weight Calculator

Developed by B.J. Devine (1974) to calculate initial drug dosages for adults. Despite this clinical origin, it became the most widely cited "ideal body weight" formula in medicine. Not intended as a personal health target.

Male: 50 kg + 2.3 kg per inch over 5 feet (60 in)
Female: 45.5 kg + 2.3 kg per inch over 5 feet

Robinson JD et al. (1983) updated the Devine formula based on a broader dataset. It uses slightly different coefficients and tends to produce lower estimates for taller individuals.

Male: 52 kg + 1.9 kg per inch over 5 feet
Female: 49 kg + 1.7 kg per inch over 5 feet

Also published in 1983, the Miller formula uses yet another set of coefficients and generally produces the lowest ideal weight estimates of the three. It tends to suggest lighter weights for shorter 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

Developed by G.J. Hamwi (1964) and used in clinical nutrition settings. Uniquely, it accounts for frame size: small-frame individuals subtract 10%, large-frame individuals add 10%. This is the only formula in the set that adjusts for skeletal variation.

Male: 48 kg + 2.7 kg per inch over 5 feet (± 10% for frame)
Female: 45.4 kg + 2.25 kg per inch over 5 feet (± 10% for frame)

The World Health Organization (WHO) defines a healthy BMI as 18.5–24.9. For a given height, this translates to a weight range rather than a single number. The BMI range is the most commonly used clinical reference for healthy weight today.

BMI = weight (kg) ÷ height² (m). Rearranged: weight = BMI × height²

Lower bound: 18.5 × height²   Upper bound: 24.9 × height²

No single formula is universally most accurate. The Devine formula was designed for drug dosage calculation, not ideal weight. The BMI healthy range (18.5–24.9) is the most widely used clinical reference today. Most practitioners recommend a healthy weight range rather than a single target number, because individual variation in muscle mass, bone density, and body proportions is too large for any formula to capture fully.

BMI is a useful screening tool at a population level but has significant limitations for individuals. It does not distinguish between muscle and fat mass, and can misclassify muscular individuals as overweight. It also ignores fat distribution (where fat is stored matters more than total amount). It is best used alongside other metrics such as waist circumference, body fat percentage, and metabolic biomarkers.

That is expected and normal — these formulas were developed in different decades for different clinical purposes. The meaningful takeaway is the range across formulas. If all four place you between 140–160 lbs, your healthy reference zone is that range, not a single number. The visual range bar above shows this spread at a glance.

There is no single answer. The BMI healthy range (18.5–24.9) gives a weight range for any height. For a 5'6" (168 cm) person, this is roughly 115–154 lbs (52–70 kg). Formula results vary within this range by 5–15 lbs depending on sex and frame size. Older adults and very muscular individuals often sit at the higher end of the range in excellent health.

The Hamwi formula (1964) accounts for frame size because people of the same height can have significantly different bone structure. A small-frame person typically weighs less than a large-frame person of the same height even at identical fitness levels. Frame size is estimated by the wrist test: wrap thumb and middle finger around opposite wrist — if they overlap, small frame; if they just touch, medium; gap between = large.