The Devine Formula

The Devine formula is the most famous ideal-body-weight equation in medicine — and one of the most misused numbers in fitness. Ben Devine proposed it in 1974 to dose drugs, not to judge bodies. Knowing that history is the key to reading its output correctly.

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The Equation

Example: a 180 cm (70.9 in) man → 50 + 2.3 × 10.9 ≈ 75.0 kg. Note the formula was stated for heights of five feet and above; below that it is an extrapolation.

Why Medicine Uses It

Several drugs — aminoglycoside antibiotics like gentamicin among them — distribute mainly through lean tissue. Dosing them on actual body weight would overdose patients carrying substantial fat mass. Devine's equation gave clinicians a bedside-simple, lean-scaled weight estimate, and it stuck: pharmacokinetics references and mechanical-ventilation tidal-volume tables still cite it half a century later. Its cousins — Hamwi, Robinson, Miller — arose in the same clinical tradition; see the ideal weight calculator guide for the four side by side.

Its Limits Outside the Clinic

As a diet target the formula has three problems. It returns a single point per height, when health evidence supports a range — the BMI 18.5–24.9 band, unpacked in the ideal weight vs BMI guide. It is blind to body composition, so a muscular person "fails" it while being demonstrably healthy — the lean body mass calculator is the better lens there. And it was never validated against health outcomes for weight-loss purposes at all.

Frequently Asked Questions

What is the Devine formula used for?
Clinical dosing. Devine proposed it in 1974 to estimate ideal body weight for calculating drug doses — notably gentamicin — and it remains standard in pharmacokinetics and ventilator tidal-volume settings.

Is the Devine formula accurate for weight goals?
It was never validated for that. It returns one point per height and ignores body composition, age, and frame. The healthy BMI range is the better reference for weight goals.

Why do doctors still use ideal body weight formulas?
Because several drugs distribute through lean tissue rather than fat, dosing on actual weight would overdose patients with obesity. Ideal body weight gives a lean-scaled estimate that is simple to compute at the bedside.