Free BMI Calculator
for 40+ Countries

BMI compresses height and weight into one number so clinicians and public-health teams can screen populations quickly. Higher BMI is associated with higher average risk of type 2 diabetes, heart disease, and some other conditions—but individual risk still depends on fat distribution, fitness, age, genetics, and labs.

BMI cannot see muscle versus fat, bone density, or where fat is stored. That is why two people with the same BMI can look and feel very different.

• Useful first pass for adults comparing weight to height
• Less reliable alone for athletes, pregnancy, older adults with low muscle, or edema
• Works best alongside waist, bloodwork, and how you feel day to day

Measure height without shoes and weight at a consistent time of day. Use the unit system your clinician prefers—metric (kg, cm) or imperial (lb, ft/in). Our calculator converts and categorizes instantly.

• Stand tall against a wall for height; avoid thick socks or bunched hair under the measuring point
• Weigh on a flat hard floor, ideally in the morning after using the bathroom
• If tracking progress, compare weekly averages instead of single daily weigh-ins
• Pick your country so categories follow the standard you care about (WHO, CDC, or Asian)

Most countries use WHO adult bands. The U.S. CDC framework aligns with those cutoffs and adds clearer obesity class detail. Many Asian health systems use lower overweight/obesity thresholds because cardiometabolic risk can appear at a lower BMI in some Asian populations.

• WHO: healthy ~18.5–24.9; overweight 25–29.9; obesity ≥30
• CDC: same adult cutoffs, with obesity Class 1–3 bands
• Asian: overweight often from ~23; obesity from ~27.5 (varies by guideline)

Treat the category as information, not a verdict. If you are underweight, overweight, or in an obesity range, consider waist-to-hip ratio, body-fat estimate, and calorie needs next—and talk with a clinician if you have symptoms or medical conditions.

• Underweight: focus on fueling, strength, and medical causes of weight loss if unintentional
• Healthy range: maintain habits; still watch waist and fitness
• Overweight / obesity ranges: prioritize sustainable nutrition, walking, and resistance training
• Athletes: confirm with body-fat % before chasing a lower BMI for its own sake

Online BMI tools are educational. They do not replace clinical assessment, especially around pregnancy, eating disorders, heart disease, diabetes management, or unexplained weight change.