Ideal Weight Calculator

Devine, Robinson and Miller formulas, and a healthy range.

Technique moves the reading more than most people expect: a waist taped at the navel and one taped at the narrowest point can differ by two inches, and impedance scales shift with hydration. Consistency of method matters more than the absolute number on any single day.

Body measurements in the United States are read against published reference tables: BMI categories from the CDC, body-fat ranges from the American Council on Exercise, and circumference standards used by the Army and Navy. BMI divides weight by height squared and cannot separate muscle from fat, so a lean, heavily built person can read as overweight.

Waist measurement and body-fat estimates fill in what the index alone misses.

Ideal-weight formulas such as Devine and Robinson were written for drug dosing rather than for judging bodies, and each produces a single point inside what is really a range. Frame size and muscularity move a sensible target well away from the formula's answer.

These scales were built on population averages, so a single reading says more about where you sit against a table than about your own health.

Fat-free mass, hydration and time of day all move a reading, and a measurement taken after a meal or a workout reads differently from one taken fasted. Trends over weeks, taken the same way, describe a body; a single figure describes a moment.

Ideal Weight Calculator sits with the rest of the library's health work, and it rests on the same body-measurement arithmetic the way a clinical reference table does. Its answer is only as good as the assumptions standing behind it.

The quantities it works from — sex, height, current weight and current body fat — are the ones a real body-measurement question actually turns on, and each carries a convention of its own, set out below.

Health figures in the United States are read against reference tables published by federal agencies and professional bodies, and those tables describe populations rather than individuals. One measurement is a data point; a series taken the same way over months is information.

Clinical guidance also shifts as evidence accumulates, which is why a range that was standard a decade ago may no longer be quoted.