Body fat percentage tells you what portion of your weight is fat versus lean mass (muscle, bone, water, organs). It's far more useful than BMI for anyone who trains — two people at the same weight can look, perform, and be built completely differently based on this one number.
How the calculator estimates body fat
We use the U.S. Navy method: it plugs your height, neck, waist (and hip for women) into a validated formula. Accuracy is ±3–4% versus DEXA — better than most home scales, and totally free.
Healthy body-fat ranges
Men: 6–13% athletic, 14–17% fitness, 18–24% average, 25%+ high. Women: 14–20% athletic, 21–24% fitness, 25–31% average, 32%+ high. Going below 6% (men) or 14% (women) impacts hormones — not a place to live long-term.
How to lower body fat correctly
Sustained calorie deficit (300–500 kcal below TDEE) + high protein (2.0–2.4 g/kg) + resistance training 3–5×/week. Cardio is optional. Rapid crash diets lose muscle first and rebound fat. Aim for 0.5–1% body-weight loss per week.
Worked example
A 175 cm man with neck 40 cm and waist 90 cm: Navy formula gives ~19% body fat. To get to 15% he'd need to drop roughly 4 kg of fat while keeping muscle — about 8–12 weeks of consistent training and dieting.
- 1Measure at the same time of day (morning, empty stomach) for consistency.
- 2Retest every 4 weeks — daily fluctuations are noise.
- 3Photos in the same lighting/pose beat any number for tracking real change.
Frequently asked questions
Q1.How accurate is the Navy method?
±3–4% vs. DEXA scans. Good for tracking trends; not a lab-grade measurement.
Q2.Should I aim for 'ripped' body fat year-round?
No. Very low body fat (<10% men, <18% women) hurts recovery, hormones, and mood. Reserve it for peak weeks, not lifestyle.
Q3.What's the fastest safe rate of fat loss?
About 1% of body weight per week. Faster than that = muscle loss and rebound.
Home body-fat estimates are approximations. For medical decisions, use DEXA or hydrostatic weighing under a professional.