BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Enter your weight and height to see where you fall on the WHO weight categories.
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Measurements convert when you switch units
The formula
Body Mass Index (BMI) is a simple measure using your height and weight to estimate body fat. Healthcare providers worldwide use it as a screening tool — though it does not directly measure body fat and may misclassify very muscular people.
Worked example
- Convert 175 cm to 1.75 m
- Square 1.75 → 3.0625
- Divide 70 kg by 3.0625 = 22.9
Result: 22.9 — Normal weight (WHO category)
Interesting facts
Invented by a Belgian statistician
Adolphe Quetelet created the "Quetelet Index" in the 1830s, long before it was renamed BMI in the 1970s by Ancel Keys.
Different cutoffs in Asia
WHO Western Pacific Region recommends overweight at BMI ≥ 23 for Asian populations, reflecting higher health risks at lower BMI values.
Not ideal for athletes
A rugby forward or bodybuilder can have a BMI over 30 while carrying low body fat — muscle weighs more than fat per volume.
Used in 200+ countries
BMI remains the most widely used population-level weight screening metric because it requires only height and weight — no special equipment.
Frequently asked questions
BMI is a useful screening tool for most adults but can overestimate fatness in muscular people and underestimate it in elderly individuals who have lost muscle mass.
For most adults, WHO defines normal weight as BMI 18.5–24.9, overweight as 25–29.9, and obese as 30 or above.
Either works — this calculator converts automatically. Use whichever units you normally measure in.
No. BMI is a screening indicator, not a diagnosis. Consult a healthcare provider for a full assessment.