BMI vs Body Fat Percentage: What's the Difference?

BMI tells you how heavy you are for your height. Body fat percentage tells you how much of that weight is fat tissue. They measure different things, and for many people they tell different stories.

When BMI and body fat disagree

Athletes, particularly those with significant muscle mass, often have a 'high' BMI but a low body fat percentage. Conversely, older adults can have a 'normal' BMI but elevated body fat — sometimes called 'normal-weight obesity'.

Which should you use?

Use both. BMI is a free, instant screening tool. Body fat percentage gives a fuller picture if you have access to a method that suits you — circumference-based estimates like the U.S. Navy method, skinfold callipers, bioelectrical impedance, or a DEXA scan.