BMI Calculator

Body mass index is your weight divided by the square of your height, and it exists because it is cheap to measure and correlates well with health outcomes across large populations. That is genuinely useful — it is why doctors, insurers and public health bodies still use it — but it is also the source of its limits.

BMI cannot distinguish muscle from fat, and it says nothing about where weight is carried. A muscular athlete can register as overweight while carrying very little body fat, and someone with a BMI in the healthy band can still carry a high proportion of abdominal fat, which is the distribution most associated with metabolic risk. It is also less reliable for older adults, whose body composition shifts, and it is read against different thresholds for South and East Asian populations, where health risks appear at lower values.

The healthy range shown alongside your result is often the more useful output, because it converts an abstract number into a weight range for your actual height. Treat the whole thing as one indicator among several rather than a verdict — waist measurement, blood pressure, activity level and family history all say things BMI cannot. Everything is calculated in your browser, so nothing you enter is sent anywhere or stored.