BMI Calculator
Calculate your body mass index from height and weight. BMI is a quick screening estimate — useful for context, but not a complete measure of health.
Enter your values
Use height in centimeters and weight in kilograms to calculate your BMI.
Quick BMI examples
How BMI is calculated
BMI is calculated by dividing body weight in kilograms by height in meters squared.
What BMI can tell you
BMI can give a rough indication of whether weight is low, normal, high or very high for a given height.
What BMI cannot tell you
BMI does not directly measure body fat, muscle mass, fitness, diet, age, sex or overall health.
BMI categories
| BMI range | Category | How to read it |
|---|---|---|
| Below 18.5 | Underweight | A low BMI range. BMI alone does not explain the cause. |
| 18.5–24.9 | Normal weight | Often considered the normal adult BMI range. |
| 25–29.9 | Overweight | A higher BMI range. Body composition still matters. |
| 30+ | Obesity | A high BMI range that may be worth discussing with a health professional. |
These ranges are commonly used for adults. They may not apply in the same way to children, pregnant people, athletes or people with unusually high or low muscle mass.
Common BMI mistakes
Treating BMI as a full health diagnosis
BMI is only a screening estimate. It cannot tell the full story about health, fitness or body composition.
Forgetting muscle mass
A very muscular person can have a high BMI even with low body fat.
Using adult BMI ranges for everyone
Adult BMI categories are not always suitable for children, teenagers or pregnancy.
Free online BMI calculator
This BMI calculator helps you calculate body mass index from height and weight. Enter height in centimeters and weight in kilograms to get an instant result.
BMI can be useful as a quick screening tool because it is easy to calculate and compare. However, it should be interpreted carefully. Health is influenced by many factors beyond height and weight.
Important note
This tool is for general information only. It is not medical advice and should not replace guidance from a qualified healthcare professional.
BMI Calculator FAQ
What is BMI?
BMI stands for body mass index. It is a calculation based on height and weight.
How do I calculate BMI?
Divide weight in kilograms by height in meters squared.
Is BMI accurate?
BMI is useful as a rough screening tool, but it does not measure body fat, muscle mass or overall health directly.
What is a normal BMI?
For adults, a BMI from 18.5 to 24.9 is commonly considered the normal range.
Does BMI work for athletes?
BMI can be misleading for athletes or people with high muscle mass because muscle adds weight.
Is this BMI calculator private?
Yes. The calculation runs locally in your browser and your input is not uploaded.