About the BMI Calculator
The BMI Calculator computes body mass index, which is weight in kilograms divided by height in metres squared. It gives a quick screening number that health professionals sometimes use alongside other measures.
BMI is only a rough guide. It does not measure body fat, muscle, age, sex or ethnicity, and it can be misleading for athletes, older adults, pregnant people and children, who use different charts. This tool is not medical advice or a diagnosis; speak to a qualified health professional about your health.
How to use it
- Enter your Height (cm).
- Enter your Weight (kg).
- Read the BMI and the general range label.
Adult ranges used
Below 18.5 is below the usual adult range, 18.5 to 24.9 is the usual range, 25 to 29.9 is above, and 30 or more is high.
Example: 70 kg and 175 cm gives 70 ÷ 1.75² ≈ 22.9.
Waist size, fitness and diet quality tell you more than BMI alone.
Real-world examples
Quick screening. 70 kg at 175 cm gives 22.9, inside the usual adult range.
Tracking a change. Record BMI alongside waist size and how you feel, not alone.
Preparing for a doctor visit. Know your number and discuss what it means for you.
Common mistakes
Entering height in metres or feet instead of centimetres. Using adult ranges for children or teenagers, who need age-specific charts. Reading a number in isolation: athletes, older adults and pregnancy change what it means.
How it works
BMI = weight in kg ÷ (height in metres)². The height you type in centimetres is divided by 100, squared, and used as the divisor. The label compares the result with the common adult cut-offs of 18.5, 25 and 30, described in neutral wording. It is a screening number and not a diagnosis.
Frequently asked questions
Is BMI accurate?
It is a screening estimate and has well-known limits.
Can I use pounds?
Convert to kg and cm first with the Unit Converter.
Is my data saved?
No.