Ideal Weight Calculator

Ideal body weight formulas were written for drug dosing, not for setting a personal target. They give a single number from height and sex alone, so they ignore build, muscle and body composition entirely.

Ideal body weight is a single number derived from height and sex, and its origin explains nearly everything about it: the four equations here were written for clinical drug dosing, where a standardised weight is needed to size a dose. All four share one shape — a base weight at five feet, 152.4 cm, plus a fixed amount for every further inch — which is why an imperial step turns up in the middle of a metric field. For a man of 178 cm, Devine takes its base of 50 kg and adds 2.3 kg for each of the 10.08 inches above 152.4 cm, arriving at 73.2 kg. Robinson, Miller and Hamwi work identically with other constants and return 71.1, 70.4 and 75.2 kg for the same man. Read the spread rather than the single figure. Nearly five kilos separate the four answers to one height, and none of them is more correct than the rest: they are four fits to four populations, not competing measurements of something real. Devine is preselected only because it is the one most often used in dosing. The limitation that matters most is what the equations are allowed to know. Height and sex go in; nothing else does. Build, muscle and body composition are absent from the arithmetic, so a muscular person reads low against all four. It is a dosing estimate, not a weight to aim at.