“Ideal weight” formulas give a rough target based on height and sex. They're simple clinical estimates — useful as a ballpark, not a precise goal, since they don't account for build, muscle, or age.
The Devine formula
This calculator uses the Devine formula, originally created for medication dosing: a base weight at five feet of height, plus 2.3 kg for each additional inch. Other formulas (Robinson, Miller, Hamwi) give slightly different numbers.
A healthy weight is a range, not a single figure. Body composition and overall health matter more than hitting an exact number — talk to a clinician for personalized guidance.
A worked example
For a man 175 cm tall, the Devine formula converts height to inches (about 68.9"), counts the inches over five feet (about 8.9), and adds 2.3 kg for each: 50 + 2.3 × 8.9 ≈ 70.5 kg, or roughly 155 lb. A woman of the same height starts from a 45.5 kg base and lands near 66 kg.
Every additional inch of height adds 2.3 kg to the target, so small differences in how you measure height noticeably shift the result — another reason to read the output as a ballpark.
Why “ideal” is a range, not a rule
The Devine formula was originally built to calculate medication doses, not as a health goal, and it ignores frame size, muscle, and age. Related formulas — Robinson, Miller, Hamwi — give slightly different answers, which is a good sign the concept is approximate by nature.
A more useful framing is a healthy range: at a given height, a band of weights corresponds to a normal BMI. What matters more than hitting any single figure is body composition, fitness, and overall health, so use the number to orient rather than as a target to chase.