Work out your BMI and see if it is in range
Calculate your Body Mass Index (BMI) in a second and interpret it: your WHO category and the healthy weight range for your height. Note: BMI is only a screening tool — we explain its limits so you do not fixate on a single number.
BMI is a screening tool: it does not tell fat from muscle. Guidance, not medical advice.
That number is only today
In the app you watch it move: weigh-ins, progress photos and the trend of the last weeks in one chart.
Start tomorrow: weigh yourself when you get up, before breakfast, and photograph the first plate of the day.
7 days free · No card · Private
What is BMI and how is it calculated?
BMI relates your weight to your height: BMI = weight (kg) divided by height (m) squared. The WHO defines four bands: underweight (below 18.5), normal weight (18.5-24.9), overweight (25-29.9) and obesity (30 or above). It is a quick, useful screen at population level, but it has one important limitation: it does NOT distinguish fat from muscle, nor where the fat sits. That is why a very muscular athlete can read "overweight" without carrying excess fat, and why an older person who has lost muscle can read "normal" with a high body fat percentage. Use it as a starting point and pair it with your waist circumference and how you actually feel.
BMI chart: normal values by WHO
The WHO thresholds for adults. The part that surprises almost everyone: in adults, BMI does NOT have different cut-offs by sex or by age. The "BMI by age" charts you find elsewhere are not part of the WHO definition; under 19 you use percentiles instead, which is a different thing.
| Category | BMI (kg/m²) | What it means |
|---|---|---|
| Underweight | < 18.5 | Worth checking with a professional |
| Normal weight | 18.5 – 24.9 | Reference range |
| Overweight | 25.0 – 29.9 | Increased risk |
| Obesity class I | 30.0 – 34.9 | Moderate risk |
| Obesity class II | 35.0 – 39.9 | Severe risk |
| Obesity class III | ≥ 40.0 | Very severe risk |
Source: World Health Organization, classification of nutritional status in adults. These are reference ranges for healthy adults, not a diagnosis or individual advice.
FAQ
What BMI is healthy?
Per the WHO, 18.5 to 24.9 counts as normal weight. Below 18.5 is underweight, 25-29.9 overweight, and 30 or more obesity. These are population-level guides, not an individual diagnosis — two people with the same BMI can be in very different shape.
Is BMI reliable?
It is a handy screening tool but a limited one: it does not tell fat from muscle or where the fat is stored. It misreads athletes (high muscle, high BMI, low fat) and older adults (low muscle, normal BMI, high fat). Pair it with waist circumference and health markers.
How is BMI calculated?
Divide your weight in kilos by your height in metres squared. For example, 70 kg and 1.75 m: 70 divided by (1.75 x 1.75) = 22.9, which is normal weight. This calculator does it for you and adds your category and your healthy weight range.
Is BMI different for men and women?
The formula and the WHO thresholds are the same for adult men and women. Women typically carry more essential fat than men at the same BMI, which is one more reason not to stop at this single number.