Body Fat Calculator

Body fat percentage is the proportion of your total body weight that is fat tissue versus muscle, bone, and organs. A 180 lb person with 25% body fat has 45 lbs of fat and 135 lbs of lean mass. Body fat percentage is more useful than BMI because it ignores muscle weight—a muscular athlete can have a high BMI but low body fat, while a sedentary person can have normal BMI but high body fat. The American Council on Exercise (ACE) defines five categories: Essential fat (10–13% for women, 2–5% for men) is what your organs need. Athletic (14–20% women, 6–13% men) suits active people. Fitness (21–32% women, 14–17% men) is healthy. Average (33–39% women, 18–24% men) is typical American. Obese (40%+ women, 25%+ men) carries health risks.

Healthy ranges vary by age and gender. For women: ages 20–39 should aim for 21–32% (fitness category), ages 40–59 for 23–33%, and 60+ for 24–35%. For men: ages 20–39 should target 14–17% (fitness), ages 40–59 for 17–19%, and 60+ for 18–20%. These ACE guidelines differ from BMI categories and are based on actual body composition research, not just height-to-weight ratios. Genetics, hormones, and metabolism influence what is achievable for you personally. A woman with a naturally larger frame will sit differently on the spectrum than a small-framed woman. Getting measured via DEXA scan, hydrostatic weighing, or professional calipers gives you accuracy; online calculators using the US Navy method provide reasonable estimates.

A calorie deficit is non-negotiable: you cannot lose fat without consuming fewer calories than you burn. Strength training preserves muscle while you lose fat, preventing the "skinny-fat" outcome where you lose weight but look softer. Aim for 0.7–1.0 gram of protein per pound of body weight daily to preserve muscle—a 150 lb person needs 105–150 grams of protein from chicken, fish, eggs, or Greek yogurt. Sleep 7–9 hours nightly; poor sleep increases cortisol (stress hormone) which promotes belly fat storage and hunger. Avoid crash diets; a sustainable 1–2 lbs per week fat loss is the US clinical recommendation. Crash dieting causes muscle loss, hormonal disruption, and rapid rebound. Combine steady calorie deficit with strength training, adequate protein, sleep, and patience—there is no shortcut.