Body mass index in metric or imperial, with the WHO and Asian cut-offs side by side
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 23 Oct 2026.BMI Calculator divides weight in kilograms by height in metres squared. 70 kg at 170 cm is a BMI of 24.2, normal weight on the WHO scale where overweight begins at 25, and overweight on the Asian cut-offs where it begins at 23. Both readings are shown, with their sources named.
Under Units, pick kg and cm or lb, ft and in.
Enter your Weight and Height.
Choose the Cut-offs: WHO international, or Asian / Indian for South Asian adults.
Read your Body mass index, its band and the Healthy range in kg and lb; Share result copies a link.
Body mass index is one division, and it has been since Quetelet described it in the 1830s: weight in kilograms over height in metres, squared. Nothing about the arithmetic is disputed.
What is disputed is where the lines go. The World Health Organization's international classification puts overweight at 25 and obesity at 30, with three obesity classes above that. The same organisation's 2004 expert consultation found that Asian populations show raised cardiovascular and diabetes risk at a lower index, and recommended 23 and 27.5 as public health action points. Indian clinical practice went further and works to overweight at 23 and obesity at 25.
A calculator that shows one of those and calls it your category has quietly made a clinical decision for a stranger. This one makes the standard a switch, names the source of each, and prints which one produced the words on screen. For many South Asian readers the two disagree, and seeing them disagree is more useful than being handed either alone.
Enter your figures in kilograms and centimetres, or in pounds with feet and inches. Along with the index you get the weight range that would place your height in the healthy band under the standard you chose, and how far outside it you are if you are outside it.
What BMI cannot do is worth saying plainly. It does not distinguish muscle from fat, so a trained athlete reads high. It says nothing about where fat sits, and waist circumference carries information BMI misses entirely. It was derived on adults, so it does not apply to children, to pregnancy, or to the very old without adjustment. It is a screening number, not a diagnosis, and the next step after a reading outside the healthy band is a conversation with a doctor rather than a decision made from a web page.
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Weight in kilograms divided by height in metres, squared. Someone of 70 kg and 170 cm divides 70 by 1.7 times 1.7, which is 2.89, giving 24.2. In pounds and inches the same division needs a factor of 703, which is what the imperial option on this page applies for you.
18.5 to 24.9 on the WHO international scale, and 18.5 to 22.9 on the cut-offs used for South Asian adults. At 170 cm that is 53.5 kg to 72 kg under the first and 53.5 kg to 66.2 kg under the second, a difference of nearly six kilograms.
A WHO expert consultation published in 2004 found that Asian populations carry raised cardiovascular and diabetes risk at a lower index than European ones, and proposed 23 and 27.5 as action points. Indian consensus guidance adopted overweight at 23 and obesity at 25, which this page offers as a switch.
No, and that is its best known weakness. Muscle is denser than fat, so a trained athlete can read as overweight or obese while carrying very little fat. BMI also says nothing about where fat sits, which is why waist measurement is often used alongside it rather than instead of it.
Not as shown here. Children are assessed against age and sex percentile charts rather than fixed adult bands, and pregnancy changes weight for reasons BMI was never meant to interpret. The categories on this page apply to non-pregnant adults, and a paediatrician or midwife is the right source otherwise.
Treat the figure as a screening result and take it to a doctor rather than acting on it alone. A single number cannot tell you whether the cause is muscle, body shape, a medical condition or diet, and the weight range shown here is a target for a conversation, not a prescription.
Rates and rules change; check the source before you rely on a figure.
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