Body Composition Analyzer
Estimate your BMI, body fat percentage, lean mass and a healthy weight range, computed live as you move the sliders. See where you sit across the body-fat spectrum.
The BMI-based estimate uses the Deurenberg equation. Adding a waist measurement blends in the US Navy circumference method for men.
BMI is a screening tool, not a verdict
BMI works at the population level but misreads individuals: it overestimates fat in muscular builds and can underestimate it in older or sedentary people. Body fat percentage and waist circumference track health risk better. The body-fat number here is itself an equation-based estimate (Deurenberg, or the US Navy method when you add a waist), not a body scan. The fitness-band labels follow the popular ACE chart, an industry source, not a clinical guideline, so read them as illustrative.
Frequently asked questions
What is a healthy body fat percentage?
For men: 10–20% is athletic to fit, 18–24% is average. For women: 18–28% is athletic to fit, 25–31% is average. Essential fat (minimum for health) is 2–5% for men and 10–13% for women. Age shifts these ranges upward slightly. These bands follow the popular ACE chart, an industry reference rather than a clinical guideline.
How accurate is BMI?
BMI is a population-level screening tool, not an individual diagnostic. It fails for muscular individuals (overestimates fat), elderly (underestimates fat), and athletes. Body fat percentage and waist circumference are more reliable indicators of health risk.
What is FFMI and why does it matter?
Fat-Free Mass Index (FFMI) measures lean mass relative to height. An FFMI of 18–20 is average for men, 20–22 is above average, and 22–25 indicates significant muscle development. FFMI above 25 is rare without pharmacological assistance (Kouri 1995, where a drug-free cohort averaged about 21.8 and all stayed at or below 25).
How to reduce body fat effectively?
Create a moderate caloric deficit (300–500 kcal/day), prioritize protein (1.6–2.2g/kg), combine resistance training with cardio, sleep 7–9 hours, and manage stress. Aim for 0.5–1% body weight loss per week to preserve muscle mass.
Learn more
Related tools
- Deurenberg P, Weststrate JA, Seidell JC (1991). Body mass index as a measure of body fatness. Br J Nutr, 65:105-114. PubMed
- World Health Organization. BMI classification for adults (underweight <18.5, normal 18.5-24.9, overweight 25-29.9, obese ≥30).
- Hodgdon JA, Beckett MB (1984). Prediction of percent body fat for U.S. Navy personnel. Naval Health Research Center.
- American Council on Exercise (ACE). Body-fat percentage categories (popular industry reference, not a clinical guideline).
- Kouri EM et al. (1995). Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clin J Sport Med, 5(4):223-228.
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