How it works
Ideal body weight (IBW) formulas were created mainly for medicine dosing, not as personal goals. Each starts from a base weight at 5 feet and adds a fixed amount per inch above that.
The Devine formula (1974) is the most widely used in clinical practice. Robinson and Miller (both 1983) refined it with newer data, and Hamwi (1964) is an older rule of thumb. The BMI range shows the much wider band of weights considered healthy for your height.
None of these formulas account for frame size, muscle mass or age, so a healthy weight for you can sit well outside any single number. Results are estimates, not medical advice.
Formula
Devine: men 50 kg + 2.3 kg per inch over 5 ft; women 45.5 kg + 2.3 kg per inch over 5 ft
Questions people ask
Which ideal weight formula is best?
None is clearly best for individuals. Devine is the clinical standard for drug dosing; Robinson and Miller tend to give slightly different values at the tall and short ends. The BMI-based range is a better guide to a healthy span of weights.
Why do the formulas give different answers?
They were fitted to different populations and data sets in different decades, and each uses its own base weight and per-inch increment.
Do these formulas work for people under 5 feet?
They were not designed for it. Below 5 ft the formulas extrapolate downward and become less reliable; the BMI range is more useful there.