BMI Calculator
Calculate your Body Mass Index (BMI) and see where it falls on the WHO classification table.
| Range | Classification |
|---|---|
| 0 – 18.5 | Underweight |
| 18.5 – 25 | Normal weight |
| 25 – 30 | Overweight |
| ≥ 30 | Obesity |
How BMI is calculated
The Body Mass Index (BMI) is obtained by dividing your weight, in kilograms, by your height squared, in meters: BMI = weight / (height × height). It is a quick and free way to estimate whether your weight is appropriate for your height.
The result is compared to the World Health Organization (WHO) classification table, which defines ranges for underweight, normal weight, overweight and obesity. BMI is a general reference and does not replace assessment by a health professional.
Frequently asked questions
What is considered a healthy BMI?
According to the WHO, a BMI between 18.5 and 24.9 is classified as normal weight for adults.
Does BMI work for children and athletes?
Not directly. Children use age- and sex-specific charts, and in athletes a high muscle mass can raise BMI without indicating excess fat.
Does BMI measure body fat?
No. It relates only weight and height, without distinguishing fat, muscle or bone, so it should be interpreted alongside other indicators.
How often should I calculate my BMI?
For general tracking, calculating it every few weeks or months is enough, since weight changes little in the short term.
How do I calculate BMI manually?
Divide your weight in kilograms by your height in metres squared. For 70 kg at 1.75 m: 70 / (1.75 × 1.75) = 22.9. In imperial units, multiply weight in pounds by 703, then divide by height in inches squared.
Is a BMI of 27 overweight?
Yes. Under the WHO chart, 25 to 29.9 is classified as overweight, 30 and above as obesity. A BMI of 27 sits in the middle of the overweight range.
Is BMI different for men and women?
The formula and the adult ranges are the same for both. Body composition does differ on average, which is one reason BMI should be read alongside waist measurement and body fat rather than on its own.
What is a healthy BMI after 60?
Some research suggests a slightly higher range, roughly 23 to 28, is associated with better outcomes in older adults. The standard chart is not age-adjusted, so discuss your own target with a doctor.
Related tools
- Scientific CalculatorTrigonometric functions, logarithms and exponentials
- Age CalculatorCalculate your exact age in years, months and days
- Pregnancy CalculatorDue date and gestational age calculator
- Financial CalculatorInstallments, simple interest and financing
- Compound InterestSimulate investment growth over time
- Tip CalculatorCalculate the tip and split the bill between people
- Fuel Cost CalculatorCalculate the fuel cost of a trip