Work out your BMI in whichever units you actually think in — centimetres and kilos, feet and inches, pounds or stone — and see where the number falls on the full WHO scale rather than getting a one-word verdict. The healthy weight range for your height is shown in the same units, so the number turns into something you can act on. BMI Prime and the Ponderal Index are there too. Just as importantly, this calculator is honest about what BMI is: a population-level screening statistic from the 1830s that cannot tell muscle from fat and is known to misclassify athletes, older adults, pregnant people and children. Those limitations sit next to the result, not in fine print. Everything is calculated in your browser.
This tool does not use any data storage or network traffic.
Height
Weight
Enter your height and weight to see your BMI.
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BMI Prime
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Your BMI divided by 25, so 1.00 is the top of the normal range.
Ponderal Index
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Weight over height cubed, which holds up better at unusual heights.
What this number can and cannot tell you
BMI is a screening statistic, not a diagnosis. It was derived in the 1830s from measurements of European men, and it is the ratio of your weight to your height squared — nothing else. It cannot distinguish muscle from fat, it does not know where on your body that weight sits, and it says nothing at all about your health, fitness or diet.
It is known to misclassify several groups in particular:
- Muscular builds. Muscle is denser than fat, so athletes routinely land in the "overweight" or "obese" ranges while carrying very little body fat.
- Older adults. Muscle mass falls with age, so a "normal" BMI can mask a loss of lean tissue.
- Children and adolescents. BMI is read against age- and sex-specific percentile charts, which this calculator does not use — its output is not meaningful for under-18s.
- Pregnancy. The figure has no useful interpretation during pregnancy.
- Differing ancestries. The risk thresholds were fitted to European populations, and several health bodies use lower cut-offs for people of South and East Asian descent.
If you want to know something about your health, this number is at best a starting point for a conversation with a doctor, and never a substitute for one.
Nothing leaves your browser
Your height and weight are used only to do the arithmetic on this page. Nothing is uploaded, nothing is stored, and reloading the page clears it all.