Body-fat percentage answers the question BMI can't: how much of you is actually fat. Healthy ranges vary by sex and shift gently with age — here are the general reference bands.
Women carry more essential fat than men for normal physiological function, so healthy female ranges sit several points higher across the board. This is biology, not a flaw — comparing a woman's body fat to a male standard (or vice versa) is meaningless.
These are broad, widely-cited ranges for adults — treat them as orientation, not precise cutoffs:
A healthy body-fat percentage rises modestly with age — an acceptable figure for a 50-year-old is a little higher than for a 20-year-old. Some loss of muscle and gain of fat with age is normal, which is also why a fixed number isn't right for everyone.
Body fat and BMI answer different questions, and they're most useful together. BMI is a quick free screen; body fat tells you what BMI can only guess at, which matters most for the muscular and the older — exactly the groups BMI misclassifies. The catch is measurement quality: a sloppy body-fat reading is worse than none. If you have a reliable figure, you can enter it in our calculator to use the lean-mass Katch-McArdle BMR.
Roughly: women fitness 21–24% / acceptable to ~31%; men fitness 14–17% / acceptable to ~24%. Women's healthy ranges are higher due to essential fat. Ranges rise gently with age.
Women carry more essential fat for normal physiological function, so healthy ranges sit several points above men's. They shouldn't be compared to a male standard.
They answer different questions and work best together. Body fat is more informative for muscular or older people, but only if measured reliably; BMI is a hard-to-get-wrong free screen.