Quick answer
The BMI calculator divides weight by height squared to estimate the relationship between body mass and height. The result helps identify adult ranges such as underweight, healthy weight, overweight and obesity.
What is BMI?
BMI means body mass index. It is a simple screening measure used to estimate whether weight is proportional to height in adults.
How to use the BMI calculator
- Enter weight in kilograms.
- Enter height in meters.
- Calculate BMI.
- Read the value and adult category.
Formula used
BMI = weight / (height x height)Example: 70 kg and 1.75 m gives BMI = 70 / (1.75 x 1.75), around 22.9.
Adult BMI category table
Adult BMI categories are commonly used for people aged 20 or older.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25.0 to 29.9 | Overweight |
| 30.0 to 34.9 | Obesity class I |
| 35.0 to 39.9 | Obesity class II |
| 40.0 or more | Obesity class III |
How to interpret the result
A BMI from 18.5 to 24.9 is commonly classified as healthy weight for adults. Values outside this range may suggest the need to review habits and seek professional assessment.
Important limitations
- BMI does not distinguish fat, muscle, bone and fluids.
- Athletes may have high BMI without excess body fat.
- Children, teenagers, pregnant people and older adults may need specific criteria.
- The result is not a medical diagnosis.
Frequently asked questions
Is BMI valid for everyone?
BMI is a general adult screening measure. Some groups need other criteria.
Does this calculator replace medical advice?
No. It is educational and does not replace a healthcare professional.