Body Fat Percentage (BF%)
The proportion of total body weight composed of adipose tissue relative to overall mass.
Clinical & Bioenergetic Overview
Body Fat Percentage divides total lipid mass (both essential fat around organs and storage fat in subcutaneous and visceral depots) by total body weight. Essential fat levels are 3% to 5% for men and 10% to 13% for women, below which endocrine collapse and health impairment occur.
Mathematical Formula & Calculation
Real-World Worked Example
A 180 lb male with 27 lbs of total fat tissue: BF% = (27 / 180) × 100 = 15.0%.
Why It Matters for Dieting
Determines the appropriate aggressiveness of a calorie deficit: individuals with higher body fat can safely tolerate larger deficits without risking muscle loss.
Frequent Mistakes
Relying on bioelectrical impedance bathroom scales, which fluctuate wildly (by 3% to 6%) based on hydration, food in the gut, and skin temperature.
Input Body Fat in Engine
Enter your body fat percentage to activate the Katch-McArdle formula.