BMI Calculator
Calculate body mass index from height and weight.
Tip: BMI is a screening number, not a diagnosis. Muscle mass, age and medical context matter.
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About this digital tool
BMI, or body mass index, is a screening measure that compares weight with height. The formula is BMI = weight in kilograms divided by height in meters squared. It is commonly used to group adults into underweight, normal, overweight and obesity ranges. BMI is quick and useful for population-level comparisons, but it does not measure body fat directly and can misclassify athletes, older adults or people with unusual body composition. Use it as a starting point, not as medical advice.
How to use
- Enter your height.
- Enter your weight.
- Read the BMI value and category.
- Use the result as a general screening estimate.
Frequently asked questions
Is BMI accurate for everyone?
No. BMI does not directly measure body fat and can be less useful for athletes, children, pregnant people or older adults.
What is the BMI formula?
BMI = weight in kilograms / height in meters squared.
What is a healthy BMI?
According to the WHO, the normal range is 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight and 30 or above is obesity.
Is BMI accurate for children or pregnant women?
No. The categories here are for adults. Children are assessed on growth charts for their age, and during pregnancy the BMI from before pregnancy is used. Ask a paediatrician or gynaecologist.