“How much should I weigh?” sounds like a question with a single correct answer. It is not — and the honest answer is not a compromise or a hedge, it is a genuine range, wide enough that two people the same height, both squarely inside it, can differ by close to 20 kilograms.
Where the range actually comes from
The CDC’s healthy BMI band runs from 18.5 to 24.9. Converted back into a weight for a specific height — weight equals BMI times height in meters, squared — that band becomes an actual range of kilograms. At 1.75 meters it spans roughly 56.7 to 76.3 kilograms; at 1.85 meters, roughly 63.3 to 85.2. Both people are unambiguously healthy by this measure, and they differ by nearly 20 kilograms at the same height. The ideal body weight calculator reports this full range for any height, along with a mid-range target of BMI 22 — chosen because a published comparison found it lands roughly in the middle of the classical formulas used for this purpose, not because 22 is somehow more “correct” than 20 or 24.
Why this site does not use the Devine formula
Most ideal-weight calculators run on the Devine formula, or its later variants by Robinson and Miller — the familiar “start at a base weight for five feet, add a fixed amount per inch” style of equation. Those coefficients could not be sourced from any document we could actually read: the paper documenting where Devine’s numbers originally came from is abstract-only, and the papers that discuss the formula describe it without printing the constants. Rather than reconstruct a health-adjacent formula from memory — which risks looking authoritative while being subtly wrong — this site runs on the CDC’s healthy BMI band instead, which is fully readable and traceable end to end.
What a target weight cannot know
It cannot see how much of a given weight is muscle. Muscle is denser than fat for the same volume, so a well-trained, muscular body can sit above the calculated range with nothing at all wrong — the same blind spot BMI has, inherited directly here since this calculator is BMI read in reverse. It also says nothing about frame size, age, or weight history, all of which a clinician would actually weigh before naming a specific number for a specific person.
How the range connects to the rest of your numbers
Weight for height is only one piece. The body fat percentage calculator answers a closer question for anyone who suspects BMI-style reasoning is misleading for their specific build, and the macronutrient split calculator turns a target calorie figure into grams of carbohydrate, protein and fat once you have a number you are actually working toward.
Why the range gets wider, not narrower, as height increases
Because the underlying relationship squares the height term, the healthy-weight range in kilograms grows faster than height itself does. Going from 1.75 m to 1.85 m — a 10-centimetre, roughly 6% increase in height — widens the healthy weight range from about 19.6 kilograms (56.7 to 76.3) to about 21.9 kilograms (63.3 to 85.2), a proportionally larger increase in the range’s width than the height increase that produced it. This is simply the area-scaling relationship discussed in area vs. volume scaling showing up in a different context — height squared behaves the same way any other squared linear measurement does, growing faster than the linear input itself.
What changed between the old and new versions of this calculator
An earlier draft of this calculator was built on the Devine formula family before the sourcing standard this site holds itself to caught the problem: the constants in that formula could not be traced to a document that was actually readable, only to secondhand descriptions of it. Rebuilding on the CDC’s published healthy-BMI band instead was not a downgrade — a peer-reviewed comparison found that a BMI of 22 lands roughly in the middle of the classical formulas anyway, which means the readable, fully sourced version and the unreadable, commonly used one arrive at essentially the same answer. The difference is that only one of them can be checked.
It is also worth remembering that “healthy” in this context describes a population-level statistical association between weight-for-height and health outcomes, not a personal guarantee in either direction — someone within the range is not automatically protected from every weight-related health risk, and someone outside it is not automatically at high risk either. The range is useful context, not a verdict, in exactly the same way BMI itself is.
How to use this
- Being inside the range is what the evidence actually supports — where inside it you personally sit is not something this calculator, or any calculator, can determine for you.
- Do not treat the midpoint as a goal. It is shown because a single figure is what most people expect to see, not because the middle of the range is healthier than either end of it.
- If the distance between your current weight and the range is large, that is a conversation for a clinician, not an arithmetic plan — how fast weight should change is a medical question, not a calculator’s to answer.
