BMI vs body fat percentage
Compare what BMI and body fat percentage estimate, how each is measured and when one may add context to the other.
BMI and body fat percentage are related but not interchangeable. BMI compares total weight with height; body fat percentage estimates what proportion of body mass is fat.
BMI requires only a scale and height measurement. It is consistent and useful for screening, but cannot separate fat, muscle, bone and water. Body fat percentage addresses composition more directly, yet the estimate depends heavily on the method.
Tape-measure formulas, skinfold calipers and bioelectrical-impedance scales are accessible but can vary with technique, hydration and device assumptions. DXA and other clinical methods may be more informative, but they are not error-free and are less convenient.
A muscular person with a high BMI may benefit from a body-composition measure for context. Someone with a healthy-range BMI may also have a relatively high fat percentage or low muscle mass. Neither figure alone establishes health.
Compare the BMI calculator with the body fat percentage calculator, and focus on repeatable trends rather than false precision.