Which IBW formula is the best?

Each estimates similar values for average heights and diverges at extremes. The Devine formula (1974) is the most cited in clinical pharmacy; Robinson (1983) and Miller (1983) tend to be slightly higher and lower respectively; Hamwi (1964) is the oldest and is mostly retained for historical comparison. We show all four plus an average so you can see the spread.

Why is my BMI healthy weight range different from the IBW number?

Because they're answering different questions. BMI says what weight produces a particular body mass index for your height — the range is 18.5 to 24.9. IBW formulas produce a single estimate optimized for medication dosing in adults. The BMI healthy range is generally a more useful target.

Do these formulas account for muscle mass?

No. None of the IBW formulas know anything about your body composition. A muscular person at the formula's predicted weight may have lower body fat than expected; a sedentary person may have higher. Pair IBW with body fat percentage if available.

Should I aim for the IBW number?

Don't optimize for a single number from a 1970s pharmacy formula. Aim for the BMI healthy range (or a body fat percentage in the fitness range), with strength performance, energy, and sleep as the qualitative checks. If you want a personalized goal weight, work with a registered dietitian — the math is the easy part.

Ideal Weight Calculator — 4 formulas

Ideal Weight Calculator

Devine, Robinson, Miller, Hamwi formulas + healthy BMI range

Implements a published clinical formula — see citation

Maintained by TheHealthTools team. Not medical advice.

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Where these formulas came from

The four ideal-body-weight formulas — Devine, Robinson, Miller, Hamwi — were developed between 1964 and 1983 by clinical pharmacists trying to dose medications more accurately in patients of unusual size. They are not, and were never, body composition prescriptions. The Devine formula is the most cited in modern pharmacy practice; the others survive mainly for historical comparison. We show all four because they diverge slightly at the extremes and the spread is informative.

For a personal weight target, the BMI healthy range (18.5–24.9) is generally a better reference. It accounts for your height directly and gives you a window rather than a single number, which is closer to how weight actually distributes in healthy populations. If you're an athlete or have unusual body composition, pair BMI with body fat percentage rather than treating either number in isolation.

Source: Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Ann Pharmacother. 2000;34(9):1066-1069.

Frequently asked questions

The ideal body weight (IBW) formulas — Devine, Robinson, Miller, Hamwi — were developed in the 1960s–80s to estimate medication dosing in patients of unusual size. They were never intended as personal goal weights. Use them as one of several reference points alongside BMI and body fat percentage.