What Is BMI?
Body Mass Index (BMI) is calculated from your height and weight: weight (kg) ÷ height (m)². It categorizes you as underweight, normal weight, overweight, or obese based on standardized ranges.
BMI Categories
- Underweight: Below 18.5
- Normal weight: 18.5 - 24.9
- Overweight: 25.0 - 29.9
- Obese: 30.0 and above
BMI Limitations
BMI doesn't distinguish between muscle and fat. Athletes and bodybuilders often have a high BMI despite having low body fat. It also doesn't account for fat distribution, which matters for health risk. Use our BMI Calculator to check your number.
What Is Body Fat Percentage?
Body fat percentage measures the proportion of your total body weight that is fat tissue. This gives a much clearer picture of your body composition than BMI alone.
Healthy Body Fat Ranges
Men
- Athletic: 6-13%
- Fitness: 14-17%
- Average: 18-24%
- Obese: 25%+
Women
- Athletic: 14-20%
- Fitness: 21-24%
- Average: 25-31%
- Obese: 32%+
Try our Body Fat Calculator to estimate your body fat percentage using measurements.
When to Use Each Metric
- Use BMI for: Quick health screening, population studies, initial assessment
- Use body fat for: Fitness tracking, body composition goals, athletic performance
- Use both for: A complete health picture, especially if you exercise regularly
Key Takeaway
Neither BMI nor body fat percentage tells the whole story alone. Use BMI as a starting point, then dig deeper with body fat percentage for a more accurate picture of your health. Our BMI Calculator and Body Fat Calculator make it easy to track both.