Ideal Weight Calculator

“Ideal body weight” (IBW) is a single target weight estimated from height and sex. It was invented for medicine, not dieting: the Devine formula was published in 1974 to standardise how much gentamicin a patient should receive. Four formulas are in common clinical use, and this tool reports all of them plus their average, because none is the one true answer — they simply disagree by a few kilograms.

Every formula shares the same shape. Convert height to inches (1 inch = 2.54 cm), take over = inches − 60 (how far you are above 5 ft), then apply a base weight plus a per-inch increment:

• Devine 1974 — male 50 + 2.3 × over; female 45.5 + 2.3 × over
• Robinson 1983 — male 52 + 1.9 × over; female 49 + 1.7 × over
• Miller 1983 — male 56.2 + 1.41 × over; female 53.1 + 1.36 × over
• Hamwi 1964 — male 48 + 2.7 × over; female 45.5 + 2.2 × over

For heights below 5 ft the same coefficients are applied with a negative over (standard clinical extrapolation), and the tool flags that estimates are least reliable at extremes of height. The numbers are computed two independent ways — once via the inch conversion and once with an algebraically-rearranged per-centimetre coefficient — so the Devine value is self-checked on every run.

The healthy-weight band is separate. It comes from the WHO BMI classification: a healthy BMI is 18.5–24.9, so for height h in metres the band is 18.5 × h² to 24.9 × h² kilograms. Unlike the IBW formulas it does not depend on sex. If you enter your current weight, the tool also computes your BMI (weight ÷ h²), your weight as a percentage of the Devine IBW, and your adjusted body weight (ABW): ABW = IBW + 0.4 × (actual − IBW). ABW is the figure clinicians use to dose weight-based drugs when a patient weighs more than their ideal weight, so the full dose is not driven by fat mass. This page is educational and is not a substitute for professional medical or dosing advice.

• StatPearls / NCBI Bookshelf — “Ideal Body Weight” (Devine formula + ABW convention)
• Robinson JD et al., Am J Hosp Pharm 1983 — Robinson IBW formula
• Miller DR et al., Am J Hosp Pharm 1983 — Miller IBW formula
• World Health Organization — healthy BMI band (18.5–24.9)

Formula coefficients and the WHO band were last cross-checked against these sources on 2026-06-09. The Hamwi formula originates in Hamwi GJ, “Therapy: changing dietary concepts,” in Diabetes Mellitus: Diagnosis and Treatment (American Diabetes Association, 1964); the Devine formula in Devine BJ, Drug Intell Clin Pharm 1974;8:650–655.