The healthy weight range is the span of body weight that keeps your BMI inside the standard "normal weight" band of 18.5 to 24.9. This calculator solves the BMI formula for weight at both ends of that band using only your height, so you can see the full range at a glance instead of computing one BMI value at a time.
How the healthy weight range is calculated
Body Mass Index (BMI) is defined as weight in kilograms divided by height in metres squared: BMI = weight / height². The CDC and WHO classify an adult BMI between 18.5 and 24.9 as "normal weight." Because height is fixed for this calculation, both cut-points can be solved directly for weight: minimum weight = 18.5 × height², and maximum weight = 24.9 × height². The midpoint is just the average of those two values.
This calculator converts your entered height to metres internally — whether you typed centimetres or inches — computes both boundary weights in kilograms, then converts the result to your selected display unit (kg or lb). No other inputs are used, which keeps the tool simple but also means it does not distinguish between individuals of the same height with very different body compositions.
Inputs and what they mean
The only required input is your standing height, measured without shoes, in either centimetres or inches. Switching the unit toggle between Metric (cm/kg) and Imperial (in/lb) converts your entered height and the displayed weight range automatically — you don't need to re-enter anything.
Height has an outsized effect on the result because the BMI formula uses height squared: a small change in height produces a proportionally larger change in the weight range. That's why the By Height Chart tab is useful — it shows how quickly the healthy range shifts across a spread of common heights.
Limits and edge cases
The standard 18.5–24.9 BMI band is not sex-specific and does not adjust for age, frame size, or muscle mass. A muscular athlete can fall above this range while carrying very little body fat, and an older adult's healthy range can shift with age-related changes in body composition. For a frame-size adjustment, see the Body Frame Size calculator; for a sex- and frame-aware target weight, see Ideal Body Weight.
A height of zero or a blank input cannot produce a range — the calculator shows a prompt asking for your height instead of a result. This tool is informational only and is not a substitute for a healthcare professional's assessment.