Body Mass Index from your height and weight, classified against the WHO adult bands.
For adults 18 and older. BMI is a screening measure, not a medical diagnosis - talk to a healthcare professional about what it means for you.
Nothing you enter is stored - this is pure arithmetic, computed and returned in the same request.
Body Mass Index (BMI) relates your weight to your height: weight in kilograms divided by the square of height in meters. Enter your height and weight in metric or imperial units and the page shows your BMI to one decimal place, with its WHO adult category, as you type.
BMI divides your weight in kilograms by the square of your height in meters (BMI = weight in kg / height in m, squared). It is a simple screening measure, not a diagnostic tool - it does not directly measure body fat and does not account for muscle mass, bone density or how fat is distributed, so it can be misleading for athletes, older adults and some other groups.
170 cm and 70 kg: 70 / (1.70 x 1.70) = 24.2, normal weight. 69 inches (5 ft 9 in) and 160 lb: 23.6, normal weight. 180 cm and 58.5 kg: 18.1, underweight. 180 cm and 81 kg: exactly 25.0, overweight, because 25 is where the overweight band starts.
The category is decided on the unrounded BMI, before it is rounded to one decimal place for display. 160 cm and 63.9 kg gives 24.96, which is shown as 25.0 but is still normal weight; 180 cm and 81 kg gives exactly 25.0, which is overweight. When a result sits on a boundary, trust the category badge rather than the rounded number.
The bands follow the WHO adult BMI table, as published by the WHO Regional Office for Europe: below 18.5 underweight, 18.5 to 24.9 normal weight, 25.0 to 29.9 pre-obesity (shown here as overweight), and 30.0 or more obesity, which WHO splits into class I (30.0 to 34.9), class II (35.0 to 39.9) and class III (40 and above). This calculator shows a single obese category without the classes. WHO has also noted that health risk can rise below 25 in some populations; this calculator uses the one global table and offers no population-specific cutoffs.
The WHO adult categories used here - underweight, normal weight, overweight, obese - only apply to adults. A child or teenager's BMI is interpreted differently, against age- and sex-specific growth percentile charts rather than these fixed cutoffs, so this calculator does not attempt to classify anyone under 18.
No. Neither your height nor your weight is written to disk, a database, a cache or a log. The site only counts that a calculation ran and which category it gave, with no measurements attached.
Underweight is below 18.5, normal weight is 18.5 to 24.9, overweight is 25 to 29.9, and obese is 30 and above. The category is decided before rounding, so a BMI of 24.96, shown as 25.0, is still normal weight.
No. It is scoped to adults 18 and older - a child or teenager's BMI needs to be read against age- and sex-specific percentile charts, not these fixed adult categories.
No. BMI is a screening measure, not a diagnosis. It does not account for muscle mass, bone density or fat distribution. Talk to a healthcare professional about what your BMI means for you.
Yes, pick metric (centimeters, kilograms) or imperial (inches, pounds) from the Units dropdown and the field labels change. Numbers already typed are not converted: they are read in the new units, so 170 typed as centimeters becomes 170 inches and is refused as an unrealistic height. Re-enter both values after switching.
Imperial height is entered in inches only. Multiply the feet by 12 and add the inches: 5 ft 9 in is 69 inches and 6 ft is 72 inches. Decimals such as 69.5 are accepted.
No. Every result is classified on the single WHO adult scale: under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, 30 and above obese. A WHO expert consultation (The Lancet 2004;363:157-163) found that many Asian populations already have a higher risk of type 2 diabetes and heart disease below 25; it kept the international categories and added 23 and 27.5 as extra points for public health action. India's 2009 consensus statement (J Assoc Physicians India 2009;57:163-70) treats 23 to 24.9 as overweight and 25 or more as obese. So a result of 24.2 reads normal weight here but would be flagged on those Asian cut-offs: read your number against them yourself, or ask your doctor which scale they use.