BMI Calculator
Calculate body mass index from height and weight. BMI is a population screening measure, not a verdict on health.
kg
cm
About this calculator
Body Mass Index is a height-to-weight ratio used as a screening number, not a diagnosis. Muscle mass, age, and body composition can place a healthy person outside the “healthy” BMI band.
Limits
- The WHO bands shown here are for adults. They are not calibrated for children, athletes, or pregnancy.
- BMI does not measure body fat, muscle, or health.
- It is a screening number, not a diagnosis.
How to calculate
Choose metric or imperial units, enter height and weight, and calculate. The result includes BMI and the WHO category.
Metric: BMI = kg / m²
Imperial: BMI = 703 × lb / in²
When to use it
- A quick check against the adult WHO bands
- Comparing metric and imperial inputs on the same person
Examples
70 kg at 175 cm
Height is 1.75 m. BMI = 70 / 1.75² ≈ 22.9, which is in the healthy range.
WHO adult BMI categories (kg/m²)
| Category | BMI |
|---|---|
| Underweight | below 18.5 |
| Normal range | 18.5–24.9 |
| Overweight | 25.0–29.9 |
| Obesity class I | 30.0–34.9 |
| Obesity class II | 35.0–39.9 |
| Obesity class III | 40.0 and above |
FAQ
Is BMI accurate for athletes?
Often not. Extra muscle can raise BMI without meaning excess fat. Treat BMI as a starting point, not a complete health picture.
Which BMI ranges are used here?
WHO adult categories: underweight below 18.5, healthy 18.5–24.9, overweight 25–29.9, and obesity 30 and above.