Ideal Weight Calculator
Ideal body weight estimates from your height, plus the healthy BMI range.
Health information notice
This tool gives a general estimate only. It is not a diagnosis, a medical device or a substitute for professional advice. Simple formulas cannot account for your individual circumstances — the assumptions and limitations listed below describe the groups this model is not suitable for.
If the result concerns you, or you are making any health decision based on it, speak to a GP, midwife, pharmacist or other qualified health professional. The health figures you enter are used only to calculate your result and are not intentionally retained — see our privacy policy.
About this calculator
"Ideal weight" formulas (Devine, Robinson) were built for medication dosing, and they remain a useful reference point — but the healthier way to read this calculator is the range it shows: the span of weights that put your BMI between 18.5 and 24.9. Anywhere in that range is defensible; the formulas mark the middle ground.
The formula
Worked example
Male, 175cm (5ft 9in): Devine = 50 + 2.3×8.9 = 70.5kg; the healthy BMI range is 56.7–76.3kg.
Common mistakes
- Treating one formula's output as a target rather than a reference.
- Ignoring frame size and muscle — a broad-framed athlete's healthy weight sits above Devine.
- Weighing daily and reacting to water-weight noise.
Frequently asked questions
Assumptions & limitations
Adult formulas; the calculator floors the height adjustment at 5ft.
Sources & verification
- Devine, B.J. (1974); Robinson, J.D. et al. (1983); Miller, D.R. et al. (1983) — The published ideal-body-weight formulas this calculator implements. Note: these were devised for drug-dose estimation, not as health targets
All sources last accessed 24 July 2026.
Spotted an error or an out-of-date figure? Report it — corrections are prioritised over all other work (see our corrections policy).