BMI Calculator
Calculate your Body Mass Index and find your weight category according to WHO standards.
Body Mass Index (BMI) is the World Health Organization's reference tool for classifying body weight in relation to height. It is calculated by dividing weight in kilograms by the square of height in metres, and allows your weight status to be compared against population reference values.
Although it is a practical and widely used indicator, BMI has important limitations: it does not distinguish between muscle mass and body fat, nor does it account for fat distribution. It should therefore always be interpreted alongside other clinical indicators such as waist circumference or body fat percentage.
Your Measurements
Health Context
Normal weightYour BMI Result
24.2
You are within the ideal range.
Health Recommendations
Nutrition
Maintain a balanced and varied diet, rich in fruit, vegetables, lean protein and healthy fats. Staying well hydrated is essential.
Physical Activity
The WHO recommends at least 150-300 minutes of moderate aerobic activity per week, plus strength training on 2 days.
Tracking
Weigh yourself monthly to detect changes. Your weight can fluctuate ±2 kg depending on the day and hydration levels.
Results are indicative only. Consult a healthcare professional for a complete assessment of your body composition.
What BMI is and how to calculate it
BMI (Body Mass Index) is a measure that relates your weight to your height to estimate whether you are within a healthy weight range. It is the indicator most used by the WHO to classify weight at the population level, because it is simple and only needs two figures: weight and height.
It is calculated by dividing weight in kilograms by the square of height in metres: BMI = kg / m². The result is compared with the WHO categories to find out whether it corresponds to underweight, normal weight, overweight or obesity.
Example
What BMI actually measures and its limits
Body mass index is calculated by dividing weight in kilograms by the square of height in metres, and was designed in the 19th century by the statistician Adolphe Quetelet to study populations, not to diagnose individuals. That is its main limitation: it relates weight to height, but does not distinguish what that weight is made of. An athlete with substantial muscle mass can register an overweight or obese BMI while being perfectly healthy, whereas a sedentary person with little muscle and high abdominal fat can sit in the normal range despite carrying real metabolic risk. It also takes no account of age, sex, ethnicity or body fat distribution.
Worked example
For a person weighing 75 kg and 1.75 m tall: BMI = 75 / (1.75 × 1.75) = 75 / 3.0625 = 24.5. That value falls within the WHO normal range of 18.5 to 24.9, though very close to the overweight threshold. If that same person weighed 80 kg, their BMI would be 80 / 3.0625 = 26.1, already in the overweight category. Note that, because height is squared, small differences in stature have a marked effect: at 1.80 m, those 80 kg would give a BMI of 24.7, back in the normal range.
BMI categories according to the WHO
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40.0 or above | Obesity class III |
How to interpret your result
Treat BMI as a first rough approximation, not a diagnosis. It is a useful screening tool for spotting trends in populations and for helping a professional decide whether to investigate further, but on its own it says nothing about your actual health. Interpreting it properly means combining it with other data: waist circumference, your level of physical activity, your body composition and blood tests such as lipid profile or blood glucose. If your result falls outside the normal range, the sensible step is to discuss it with your doctor or a registered dietitian before making decisions about your diet, and to be wary of any plan promising rapid changes without professional supervision.