Body mass index is a quick screening ratio based on height and weight. It can help describe a broad weight range, but it cannot diagnose health or account for every body type.
The BMI formula
BMI is calculated by dividing weight in kilograms by height in metres squared. If you use pounds and inches, convert them first or use the unit fields provided by the calculator.
For example, 70 kg and 1.75 m gives a BMI near 22.9. The number is a screening result, not a complete health assessment.
How to read the result
Adult screening ranges are commonly grouped as underweight, healthy range, overweight and obesity. These ranges are population-level guidance and should be interpreted with age, muscle mass, medical history and other measurements.
When BMI needs context
Athletes with high muscle mass may have a higher BMI without excess body fat. Pregnancy, growth, illness and ethnicity can also change how the result should be understood. Speak with a qualified clinician for personal guidance.
- Use the same unit system each time.
- Track trends instead of reacting to one reading.
- Pair BMI with waist measurement and clinical advice when appropriate.
Frequently asked questions
Is BMI a diagnosis?
No. BMI is a screening indicator and should not be used by itself to diagnose health conditions.
Can children use adult BMI ranges?
Children and teens require age- and sex-specific growth charts. Adult ranges are not a substitute for pediatric guidance.