BMI calculator
Calculate your body mass index and see where you stand per the WHO.
- Instant
- Free
- Private (processed locally)
- No sign-up
What is BMI?
The body mass index (BMI) is a ratio between weight and height, used worldwide to quickly estimate an adult’s build. It is recommended today by the World Health Organization as a simple benchmark to place a weight against a range considered healthy.
How to use the BMI calculator
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Enter your weight
Indicate your current weight in kilograms.
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Enter your height
Indicate your height in centimeters.
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See your BMI
Your index and the matching category (per the WHO) appear immediately, with a visual gauge.
Interpreting your result
According to WHO thresholds for adults:
- Under 18.5 — underweight
- 18.5 to 25 — normal weight
- 25 to 30 — overweight
- 30 and above — obesity
The tool’s colored gauge places your result on this scale for an instant read.
The limits of BMI
BMI is an excellent statistical indicator, but it has limits: it does not directly measure fat mass and does not account for fat distribution or muscle mass. Waist circumference or a body-composition analysis provide complementary information.
This tool is provided for information only and does not replace the advice of a health professional. If in doubt about your weight or health, consult a doctor.
Frequently asked questions
How is BMI calculated?
BMI is calculated by dividing weight (in kilograms) by the square of height (in meters): BMI = weight ÷ height². For example, for 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) = 22.9.
What are the BMI categories according to the WHO?
The World Health Organization uses: under 18.5 = underweight; 18.5 to 25 = normal weight; 25 to 30 = overweight; 30 and above = obesity. These thresholds apply to adults aged 18 to 65.
Is BMI reliable for everyone?
BMI is a population indicator, not an individual diagnosis. It does not distinguish fat mass from muscle mass: a very muscular athlete may show a high BMI without excess fat. It is also unsuitable for children, pregnant women and older adults.
What is the ideal BMI?
The so-called “normal” zone is between 18.5 and 25. Within this range there is no single ideal value: your healthy weight depends on your build, your muscle mass and your overall health.
Are my measurements saved?
No. The calculation is done in your browser and no health data is sent or stored. Your privacy is respected.