BMI and reference weight
Body mass index from height and weight, with the weight each cut-off corresponds to at your height.
Body mass index is weight in kilograms divided by height in metres squared. This page shows that number, and what each cut-off works out to in kilograms at your height. It does not say which band you are in — that is a medical judgement, and the same number means different things depending on muscle, age and build.
Height and weight
What you enter is saved in this browser, so it is still here next time
Body mass index
BMI
22.49
kg ÷ m²
Weight at a BMI of 22
63.6 kg
- Against your current weight
- 1.4 kg above
A point commonly used as a reference for the arithmetic
What each cut-off weighs at your height
| BMI | Weight there | From now |
|---|---|---|
| 18.5 | 53.5 kg | −11.5 kg |
| 23 | 66.5 kg | +1.5 kg |
| 25 | 72.3 kg | +7.3 kg |
| 30 | 86.7 kg | +21.7 kg |
This page does not say which band you fall in. BMI knows only height and weight, so it cannot tell muscle from fat, and the same number means different things for different people.
This is a statistical measure, not a medical diagnosis. Judgements about your health come from examination and tests, made by a doctor. The height and weight you enter stay in this browser and are not sent anywhere.
Make a link with these numbers
Opening the link fills this screen with the same values. Useful for going through it with a partner, or for comparing two sets of conditions.
Weight divided by height squared
Height is taken in cm, converted to metres and squared. At 170 cm and 65 kg, 1.7 × 1.7 = 2.89 and 65 ÷ 2.89 = 22.49. The value is shown to two decimal places. A height of 0 cannot be divided by, so no result is given. At the same weight, 5 cm of height moves BMI by about 1.3 — 175 cm and 65 kg is 21.22. Because the denominator is squared, height moves the number more than weight does.
The reference weight is BMI 22 solved backwards
The weight at which BMI is 22 for your height = 22 × height(m)². At 170 cm that is 22 × 2.89 = 63.58 kg, and a person at 65 kg is noted as 1.4 kg heavier. A difference under 0.05 kg counts as the same. At 160 cm it is 56.3 kg; at 180 cm, 71.3 kg. 22 is used as the axis of the calculation because it is a point often cited in statistics, not because it is a target that suits everyone.
The cut-off table has four rows and highlights none of them
18.5, 23, 25 and 30 are solved the same way into kilograms at your height. At 170 cm they are 53.5, 66.5, 72.3 and 86.7 kg, and the right-hand column subtracts your weight, so at 65 kg it reads −11.5, +1.5, +7.3 and +21.7 kg. The values are the cut-offs used by the Korean Society for the Study of Obesity and the WHO Western Pacific region. Not highlighting your row is deliberate — the moment a row is highlighted it becomes a verdict on which band you are in. The page shows where the numbers sit and says nothing about what they mean.
What this number does not see
BMI is built from height and weight alone, so it knows nothing of age, sex, muscle mass, body fat or waist size. People with a lot of muscle read high and people with little read low, and the same number does not mean the same thing at twenty and at seventy. Children and adolescents need to be read on age- and sex-specific percentile charts, which this page does not have. It is a calculation of a statistical position, not a diagnosis.
Common questions
QWhy is there no verdict?
BMI only knows your height and weight, so it cannot tell muscle from fat. Athletes read high and people with little muscle read low. The number and the cut-offs are facts and are shown as such; what they mean for you is for a doctor who has actually seen you.
QWhere does the reference weight come from?
It is the weight at a BMI of 22, a point often cited as where illness rates sit lowest in population statistics. It is useful as a reference for the arithmetic, not as a target in itself.
QWhere do my height and weight go?
Nowhere. There is no server here to receive them; the calculation finishes in the browser and the values stay in it. Pressing reset clears them too.
QWhat weight is BMI 22 at 160 cm?
22 × 1.6² = 22 × 2.56 = 56.3 kg. At the same height BMI 18.5 is 47.4 kg, 23 is 58.9 kg and 25 is 64 kg. Change the height to 160 and the table shows exactly these figures.
QCan it be used for children or teenagers?
The formula is the same, so a number comes out, but during growth the same BMI means different things depending on age and sex and has to be read on percentile charts. The cut-offs here are for adults and the page has no such charts, so a child's figure belongs on the growth chart a paediatrician uses.