About this calculator

• Supports three methods:
  • BMI method (Deurenberg): uses height, weight, age, and sex.
  • U.S. Navy method: uses height + neck + waist (and hip for women).
  • YMCA method: uses waist + weight.
• Outputs: % body fat, fat mass, lean mass, and a category label by sex.

How to measure (tape-measure tips)

• Neck: just below the Adam’s apple, tape level and snug, not tight.
• Waist: at the navel (natural waist), relaxed abdomen, after exhaling normally.
• Hips (women): widest point over the buttocks.
• Take 3 readings for each site and use the average. Measure skin on, not over clothing.

What your result means

• Body fat % = proportion of body weight that is fat.
• Fat mass = body weight × body fat %; Lean mass = weight − fat mass (includes muscle, bone, organs, water).
• Categories are guides; athletic level, age, and genetics matter. Track change over time (every 2–4 weeks).

Typical categories (used in the tool)

• Men:
  • Essential: ~2–5%
  • Athletes: ~6–13%
  • Fitness: ~14–17%
  • Average: ~18–24%
  • Above average: 25%+
• Women:
  • Essential: ~10–13%
  • Athletes: ~13–20%
  • Fitness: ~21–24%
  • Average: ~25–31%
  • Above average: 32%+

Accuracy & limitations

• BMI method: can overestimate in muscular builds and underestimate in low-muscle individuals.
• Circumference methods (Navy/YMCA): very sensitive to tape accuracy and where you measure; take averages.
• Hydration, recent meals, posture, and time of day introduce noise—measure under similar conditions (morning, after restroom, before eating).
• Gold-standard tools (e.g., DEXA) are more precise but not always necessary for trend tracking.

Tips for better tracking

• Pick one method and stick to it.
• Measure at the same time of day, under similar conditions.
• Use a flexible, non-stretch tape; keep it level and snug.
• Focus on progress + how you feel/performance, not a single number.

FAQs

• Which method is “best”?
  None is perfect—BMI is simplest, Navy/YMCA add shape info. Choose one and be consistent.
• Do I need to lose fat to be healthy?
  Not always. Health is multifactorial (fitness, labs, sleep, stress, habits).
• Can I spot-reduce fat?
  No—fat loss is systemic. Combine nutrition, resistance training, cardio, and sleep.
• What about athletes or older adults?
  BMI-based estimates skew in both groups; circumference or DEXA trends are often more useful.
• Medical advice?
  This is educational only; discuss goals and results with a professional.