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Body Fat Calculator

Calculate your body fat percentage using various proven methods

Body Fat Calculator Guide: Measure Body Fat Percentage with Multiple Methods

A body fat calculator estimates body fat percentage (%BF) using field methods such as the U.S. Navy tape equations, BMI-based formulas, or skinfold equations (e.g., Jackson-Pollock). While not laboratory-grade, these methods are practical for tracking trends.

What is Body Fat Calculator?

The body fat calculator converts circumference or skinfold inputs into an estimated %BF and often derives lean body mass (LBM). It’s useful for athletes, weight management, and general health tracking.

How to Use the Body Fat Calculator

  1. Select a method (e.g., U.S. Navy, BMI-based, or skinfold).
  2. Enter measurements (e.g., height, neck, waist, hip for women) following the on-screen placement guide.
  3. Calculate to see %BF and derived LBM.
  4. Repeat at the same time of day and with consistent posture to track trends.
  5. Optionally compare across methods, but stick to one for progress.

Formulas & Methods

  • U.S. Navy method (examples; log base 10, measures in cm):
    • Men: %BF = 86.010·log10(waist - neck) - 70.041·log10(height) + 36.76
    • Women: %BF = 163.205·log10(waist + hip - neck) - 97.684·log10(height) - 78.387
  • BMI-based estimate (Deurenberg): %BF ≈ 1.20·BMI + 0.23·Age - 10.8·Sex - 5.4 (Sex: male=1, female=0).
  • Skinfolds (Jackson-Pollock): Sum of caliper sites (3/7-site protocols) → body density via regression → %BF = 495/BD - 450 (Siri).

Assumptions & limitations

  • Tape tension, caliper skill, hydration, and ethnicity affect accuracy.
  • Use the same method and protocol for trend tracking.
  • Laboratory methods (DEXA, Bod Pod) provide reference values.

Examples

Example A — Navy method (male)
Height 178 cm, Neck 39 cm, Waist 84 cm:
%BF ≈ 86.010·log10(84-39) - 70.041·log10(178) + 36.76 → ~15–16% (illustrative).

Example B — BMI-based
Age 32, Male, BMI 25.0: %BF ≈ 1.20×25 + 0.23×32 - 10.8×1 - 5.4 ≈ 18%.

| Method | Inputs | Output | |---|---|---:| | U.S. Navy (male) | height, neck, waist | %BF estimate | | U.S. Navy (female) | height, neck, waist, hip | %BF estimate | | BMI-based | BMI, age, sex | %BF estimate |

Pro Tips & Best Practices

  • Measure first thing in the morning under similar hydration for consistency.
  • For tapes, measure at end of a normal exhale; avoid sucking in the abdomen.
  • Use three repeats per site and average for skinfolds.
  • Track trend lines weekly/bi-weekly rather than day-to-day noise.
  • Pair with waist and weight for a fuller picture of recomposition.

Related Calculators

FAQ

Q: Which methods does this body fat calculator use?

A: Common options include the U.S. Navy tape method, BMI-based estimates, and Jackson-Pollock skinfold formulas.

Q: How accurate is the Navy method?

A: It’s a practical field estimate; accuracy depends on consistent tape placement and posture.

Q: Do I need a DEXA scan?

A: DEXA is a reference method but not necessary for progress tracking—use the same method consistently.

Q: What are typical healthy ranges?

A: Ranges vary by sex and age; many guidelines cite ~10–20% for men and ~18–28% for women, but context matters.

Q: Can hydration affect readings?

A: Yes—hydration and timing influence circumference and skinfold readings; measure under similar conditions.

Compliance note: Informational only; not medical advice.

Call to Action

Choose a method, take careful measurements, and track your %BF weekly—consistency beats perfection for actionable trends.