BMI Calculator
Check your Body Mass Index, see your weight category and find the healthy weight range for your height.
What is BMI? (from database)
Body Mass Index (BMI) is a quick screening number that relates your weight to your height. It does not measure body fat directly, but for most adults it tracks health risk well enough that clinicians use it as a first check.
How BMI is calculated
Metric: BMI = weight (kg) ÷ height (m)²
US units: BMI = 703 × weight (lb) ÷ height (in)²
US units: BMI = 703 × weight (lb) ÷ height (in)²
BMI categories for adults
| Category | BMI range |
|---|---|
| Underweight | < 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obesity | ≥ 30 |
Where BMI falls short
- Athletes: extra muscle reads as extra weight, so BMI can overstate fat.
- Older adults: lost muscle can hide excess fat behind a normal BMI.
- Body composition: two people with the same BMI can carry very different amounts of fat.
Pair BMI with a body fat estimate for a fuller picture — try our body fat calculator.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 counts as the healthy range. Where you sit inside that range still depends on muscle mass, age and body composition.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so muscular people often read as overweight by BMI alone. Pair BMI with a body fat measurement for a fuller picture.
References
- World Health Organization. A healthy lifestyle — WHO recommendations: body mass index. WHO, 2010.
- CDC. About Adult BMI. Centers for Disease Control and Prevention, 2022.
This calculator provides general estimates for educational purposes only and is not medical advice. Talk to your doctor or a registered dietitian before making significant changes to your diet or exercise routine.