Healthy Weight Range Calculator

This calculator uses the Robinson formula, a sex-specific equation for estimating ideal body weight from height alone. It gives you a single center-point number, then this tool builds a healthy range of roughly ±10% around it — enough room to account for normal differences in frame size and build without pretending there's one exact "correct" weight for your height.

The formula itself is simple: for men, it starts at 52 kg and adds 1.9 kg for every inch of height over 5 feet; for women, it starts at 49 kg and adds 1.7 kg per inch over 5 feet. That result is converted to pounds for display. Because the starting weight and the per-inch increment are both different for men and women, two people of the same height get different center-point numbers — unlike a plain BMI range, which is sex-neutral and treats a 5'10" man and a 5'10" woman identically.

Robinson's formula dates to 1983 and is one of several similar "ideal body weight" equations developed for estimating medication dosing, not for diagnosing whether an individual's weight is healthy. It doesn't account for frame size, muscle mass, or body composition, which is exactly why this calculator treats its output as the center of a range rather than a single target. It also nudges the upper bound higher as your selected activity level increases — from no adjustment at sedentary up to 15% higher for athletes — since more training volume typically means more muscle mass, which pushes healthy body weight up without reflecting excess fat.

Age isn't part of the calculation: there's no validated formula that shifts a "healthy weight" target based on how old you are. That said, general guidance for adults over 65 tends to favor a more flexible reading of weight ranges, since some research links a slightly higher body weight in older adults to better outcomes during illness or recovery. If that applies to you, treat this range as a looser guide rather than a strict target, and talk to a doctor about what's right for your situation.