Healthy Weight Calculator
Enter your height and see the weight range that sits inside the healthy BMI band — plus where every other category falls, in pounds or kilograms.
Height is the only input, because that is all the body mass index uses. No age, sex or build goes into the answer — which is the method’s convenience and its main weakness at the same time.
Where the categories fall
| Category | BMI | Weight |
|---|
The boundaries are round numbers chosen for population statistics, not points where anything changes in the body. A pound either side of a line makes no practical difference.
- Muscle versus fat. Weight is weight to the formula. A heavily trained athlete often reads as overweight while carrying very little fat.
- Where the fat sits. Abdominal fat carries more risk than the same weight on hips and thighs. A waist measurement picks that up; height and weight cannot.
- Ancestry. Several countries use lower cut-offs for people of South Asian and East Asian descent, because risk appears at lower BMI values.
- Age and life stage. Older adults may do better slightly above the band, and children, pregnancy and breastfeeding are assessed on entirely separate guidance.
A useful companion measure that takes ten seconds: keep your waist under half your height. It captures the abdominal fat this page is blind to.
| Severe thinness | under 16 |
| Moderate thinness | 16 – 17 |
| Mild thinness | 17 – 18.5 |
| Healthy | 18.5 – 25 |
| Overweight | 25 – 30 |
| Obese class I | 30 – 35 |
| Obese class II | 35 – 40 |
| Obese class III | 40 and above |
The scale above splits the thin end at 16.5 rather than at 16 and 17, matching the reference tool. Read its lowest tick as approximate.
Why the answer is a range
Ask what someone of a given height should weigh and the honest answer is a span of twenty or thirty pounds, not a figure. That span exists because the healthy category of the body mass index is itself a span: a BMI from 18.5 up to 25. Fix the height and those two boundaries become two weights, and everything between them counts as healthy.
The width is not vagueness. People of identical height differ in frame size, bone density, muscle and where they store fat, and all of that sits inside a single BMI reading. A range acknowledges that a taller-framed, heavier-boned person and a lightly built one can both be perfectly well at weights a long way apart.
How the number is worked out
BMI is weight in kilograms divided by height in metres squared. Rearranged, it gives weight from a BMI and a height, and that rearrangement is the whole calculator.
lower weight = 18.5 × height(m)2
upper weight = 25 × height(m)2
Worked through for 170 cm
height2 = 1.70 × 1.70 = 2.89 m2
18.5 × 2.89 = 53.5 kg · 25 × 2.89 = 72.3 kg
In pounds
the kilogram figures are converted, not recalculated — 53.5 kg is 118 lb, 72.3 kg is 159 lb
Notice what is not in there: no age, no sex, no measure of build. That is why the same range comes back for a nineteen-year-old and a seventy-year-old of the same height, and it is the single biggest thing to hold in mind when reading the result.
One detail worth stating because it trips people up. The pound figures on this page are produced by working the weight out in kilograms and converting, rather than by the shortcut formula that multiplies pounds by 703 over height in inches squared. The two agree almost always and differ by a pound at a handful of heights.
Reading the scale
The coloured band shows every BMI category translated into weights for the height you entered, with the boundary figures sitting on the joins. It is deliberately schematic rather than a true axis: drawn to scale, the healthy band would be a narrow sliver and the top class would run off the page, which would make the categories that matter least the most prominent.
The boundaries themselves are round numbers picked for population statistics. There is nothing that changes inside the body as the scale crosses from 24.9 to 25.1. A person sitting a pound over a line and a person sitting a pound under it are, for every practical purpose, in the same position.
The lowest boundary on this scale is a BMI of 16.5, matching the reference tool. The World Health Organization actually splits the thin end more finely than that — severe thinness below 16, moderate from 16 to 17, mild from 17 to 18.5 — so treat that first tick as approximate rather than as a formal cut-off.
What BMI cannot see
BMI has survived since the 1830s because it needs only two measurements and predicts population health outcomes reasonably well. It was never designed to assess an individual, and the gap shows in four places.
It cannot tell muscle from fat. Weight is weight to the formula. A heavily trained athlete routinely reads as overweight or obese on BMI while carrying very little fat, and someone with low muscle mass can sit inside the healthy band with a high fat percentage — a pattern common enough in older adults to have its own name.
It ignores where fat sits. Fat around the abdomen carries more cardiometabolic risk than the same weight on hips and thighs, and BMI cannot distinguish them. A waist measurement, or waist divided by height, picks this up and takes ten seconds with a tape.
It squares height, and people are not squares. The exponent of two is an approximation that suits average heights and drifts at the extremes, tending to read tall people as heavier than they are and very short people as lighter.
It uses one set of cut-offs for everyone. Risk of type 2 diabetes and heart disease appears at lower BMI values in South Asian and East Asian populations, which is why several countries apply lower thresholds than the international ones used here.
Better questions than "what should I weigh"
If the aim is to know whether your weight is a problem, the range on this page is a starting point and a poor stopping point. Three things tell you more.
Waist-to-height ratio. Keeping your waist under half your height is a simple, widely endorsed rule that captures abdominal fat, which is what BMI misses most.
The direction of travel. A stable weight inside or slightly outside the band matters far less than a steady climb or an unexplained fall. Unintentional loss in particular is worth a conversation with a doctor rather than celebration.
The markers themselves. Blood pressure, fasting glucose or HbA1c, lipids and cardiorespiratory fitness are what the weight is a proxy for. If those are good, a BMI of 26 is a very different situation from one where they are not.
Where the categories came from
The index was devised by the Belgian statistician Adolphe Quetelet in the 1830s as a way of describing populations, and it carried his name for a century and a half. It became "body mass index" in a 1972 paper by Ancel Keys, which found it the best of several simple weight-for-height indices as a proxy for body fat — while explicitly noting it was suitable for population studies rather than individual diagnosis.
The 18.5 to 25 band and the obesity classes were set by the World Health Organization in the 1990s, chosen because mortality and disease risk in large cohorts rose outside them. They are statistical thresholds derived from mostly European-ancestry populations, which is precisely why the question of whether one set of cut-offs suits everyone has stayed open.
When this calculator does not apply
Several groups should not read these bands as written. Children and adolescents are assessed on age and sex specific percentile charts, because a growing body's composition changes month to month. Pregnant and breastfeeding women are assessed against pre-pregnancy BMI using separate gain guidance. Older adults may do better slightly above the standard band, and there is reasonable evidence that being at the very bottom of it carries risk after seventy. Competitive athletes and anyone with a lot of muscle will read high for reasons that are not fat, and people with conditions that affect fluid balance or limb loss cannot be assessed by weight-for-height at all.
If you want a figure that does account for sex and frame, the ideal weight calculator uses equations built for that, and the BMI calculator works the other way round if you already know your weight. For what BMI cannot see, the body fat calculator estimates composition from tape measurements.
Frequently asked questions
What is a healthy weight for my height?
It is a range rather than a number, and this page works it out from your height alone. The range spans a BMI of 18.5 to 25, so a person of 5 ft 6 in lands somewhere between about 115 and 155 pounds, and someone of 170 cm between about 53 and 72 kilograms. The band is deliberately wide because two people of the same height can both be healthy at weights fifteen kilograms apart.
Why does the calculator not ask my age or sex?
Because BMI does not use them. The same height gives the same range for everyone, which is both the method's convenience and its main weakness. Age and sex genuinely change what a sensible weight looks like, and equations that do account for them, such as the ones behind an ideal weight estimate, will give you a narrower and different answer.
Is BMI accurate for muscular people?
No, and this is its best-known failure. BMI weighs you and squares your height; it has no way of telling muscle from fat. A rugby forward and a sedentary person of the same height and weight get identical results. If you carry a lot of muscle, expect the number to place you higher than your body composition warrants, and treat a waist measurement or a body fat estimate as the more informative figure.
What if I am just outside the healthy range?
A pound or two either side of a boundary means very little. The cut-offs are round numbers chosen for population statistics, not thresholds where anything changes in the body, and your weight naturally swings by a couple of kilograms across a week with hydration, food in the gut and hormonal cycles. What is worth attention is a sustained trend over months, not which side of a line you land on today.
Does a healthy BMI mean I am healthy?
Not on its own. Blood pressure, blood sugar, cholesterol, fitness, sleep and smoking all matter more to health outcomes than which BMI band you sit in, and it is entirely possible to be inside the range with poor markers or outside it with good ones. Read the range as one screening number among several rather than a verdict.
Should the same range apply to everyone?
There is good evidence it should not. Health authorities in several countries use lower cut-offs for people of South Asian, Chinese and other Asian ancestry, because cardiometabolic risk appears at lower BMI values in those populations. The World Health Organization has discussed additional trigger points around 23 for public health action. This calculator uses the standard international bands, so if that guidance applies to you, read the boundaries as sitting a little lower.
Does this work for children?
No. Children and teenagers are assessed with age and sex specific percentile charts rather than fixed BMI cut-offs, because body composition changes a great deal through growth. A fixed adult band applied to a twelve-year-old will usually be wrong in one direction or the other. Ask a paediatrician or use a growth chart designed for the age instead.
Does it apply during pregnancy?
No. Weight gain in pregnancy is expected and is assessed against pre-pregnancy BMI using separate guidance, not against a fixed range. Reading a normal pregnancy weight against these bands would be misleading. Ask your midwife or doctor what gain is appropriate for you.
This calculator is a general screening tool and is not medical advice. A weight inside the band is not a clean bill of health and a weight outside it is not a diagnosis; BMI cannot see body composition, fat distribution, fitness or any blood marker. It does not apply to children, to pregnancy or breastfeeding, or to anyone whose body composition is unusual for their height. Discuss any concern about your weight with a doctor rather than acting on a number from a web page. If thinking about your weight or your eating is affecting your daily life, support is available — in the US, the National Alliance for Eating Disorders helpline is free and staffed by clinicians on 1-866-662-1235. More about how we build and check these tools is on our About page, and our Privacy Policy explains what we do and do not collect.