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Instantly calculate your Body Mass Index. And because BMI doesn't tell the whole story, we also show your waist-to-height ratio, BMI Prime and an estimate of your body fat, for a fairer picture of your health.
Optional, for a fuller picture than BMI alone
People of Asian descent have lower risk thresholds (overweight from 23, obesity from 25).
Enter your height and weight for an instant result.
| BMI (kg/m²) | Category |
|---|---|
| < 18,5 / < 18.5 | Underweight |
| 18,5 tot 24,9 | Healthy weight |
| 25,0 tot 29,9 | Overweight |
| 30,0 tot 34,9 | Obese class I |
| 35,0 tot 39,9 | Obese class II |
| ≥ 40,0 | Obese class III |
People of Asian descent: overweight from BMI 23 and obesity from 25 (WHO Western Pacific).
BMI is calculated by dividing your weight in kilograms by the square of your height in metres:
BMI = weight (kg) ÷ height(m)²
Example: 72 kg at 1.75 m → 72 ÷ (1.75 × 1.75) = 23.5.
BMI can't tell muscle from fat and doesn't see where fat sits. The waist-to-height ratio (waist ÷ height) does capture central fat: a value below 0.5 is considered healthy. That's why this tool combines BMI with your waist ratio and body fat.
You calculate BMI by dividing your weight in kilograms by the square of your height in metres. The formula is: BMI = weight (kg) ÷ (height in metres × height in metres). Example: 72 kg at 1.75 m gives 72 ÷ (1.75 × 1.75) = 23.5.
For adults, a BMI between 18.5 and 24.9 is considered a healthy weight. Below 18.5 is underweight, 25 to 29.9 is overweight and 30 or above is obese. For people of Asian descent the thresholds are lower: overweight from 23 and obesity from 25.
BMI is a useful first indicator, but it doesn't distinguish muscle from fat and doesn't account for where fat sits. A muscular athlete can have a high BMI with no health risk. That's why we also show your waist-to-height ratio and an estimate of your body fat.
The waist-to-height ratio is your waist circumference divided by your height. A value of 0.5 or higher signals elevated risk from central fat. The rule of thumb: keep your waist under half your height.
No. For children and teenagers (ages 2 to 18) BMI is assessed using age- and sex-specific percentiles, not the fixed adult thresholds. Consult a doctor for children.
Yes, the CalorForm BMI calculator is completely free and requires no account. If you then want to track your calories, macros and progress to reach your goal weight, you can with CalorForm.
This calculator is for informational purposes and does not replace medical advice. For questions about your weight or health, always consult a doctor or dietitian.