BMI Calculator
BMI (Body Mass Index) is a simple measure of the relationship between your weight and height. Enter your details below to calculate your BMI instantly.
Calculate Your BMI
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What is BMI and how is it calculated?
BMI is calculated using the formula: **BMI = weight (kg) ÷ height² (m²)**.
It is a simple screening tool that WHO uses to classify weight at the population level. It is *not* a diagnostic tool — it is not sufficient on its own to assess health risk at the individual level.
Limitations of BMI
- Does not account for muscle mass — muscular people can be classified as "overweight"
- Does not distinguish between fat and muscle
- Does not account for where fat is stored (belly fat vs. subcutaneous fat)
- Can be misleading for older adults (lower muscle mass)
- Does not apply directly to children
Frequently Asked Questions
What is a good BMI?
WHO defines normal weight as BMI 18.5–24.9. Below 18.5 is underweight, 25–29.9 is overweight and 30 or more is obese. Keep in mind that BMI is a rough measure and doesn't account for muscle mass, body fat percentage or where fat is stored.
Is BMI accurate for muscular people?
No — BMI can overestimate risk for muscular individuals because muscle weighs more than fat. A fit person may have BMI 27 (overweight) but with low body fat and excellent health. FFMI and body fat percentage give a more accurate picture for those who train regularly.
What is the difference between BMI and body fat?
BMI is calculated only from weight and height and says nothing about body composition. Body fat (%) actually measures what proportion of your body is fat. Two people with the same BMI can have completely different body fat percentages. For health assessment, body fat and waist circumference are often more informative.
How do you calculate BMI manually?
BMI = weight (kg) ÷ (height (m) × height (m)). Example: 75 kg and 175 cm → 75 ÷ (1.75 × 1.75) = 75 ÷ 3.0625 ≈ 24.5.
Can BMI be used for children?
For children (2–18 years), BMI-for-age and sex is used and interpreted against growth charts, not against the adult thresholds 18.5/25/30. Always use child-specific tools and consult a healthcare provider.
Understand your body — not just a number
BMI is a starting point. Log food against your calorie goal and track how your body actually responds.