11 Smart Scale Metrics Explained: Body Composition, Accuracy, and How to Use Them

2. Body Fat Percentage

Body fat percentage estimates how much of your total weight is fat tissue. Smart scales use bioelectrical impedance analysis (BIA), which sends a safe electrical signal through the body and gauges resistance: fat resists electricity more than muscle. Eight-electrode scales that contact both hands and feet offer segmental readings and usually improve estimates versus foot-only models. Still, BIA is sensitive to hydration, recent meals, and exercise, so a single reading isn’t definitive. Healthy body fat ranges vary by age and sex; adult males often fall into roughly 10–20% for many healthy ranges, while adult females usually range higher. These are broad guides, not strict thresholds. For people who train heavily, body fat readings can misclassify dense muscle as higher weight but show lower fat if algorithms account for lean mass. Use body fat percentage trends over weeks and months to judge fat loss or gain. If you live far from medical imaging like DEXA, smart-scale trends offer practical monitoring—just keep measurement conditions consistent and avoid treating every value as exact.