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📏 Body Fat Calculator

Calculate body fat percentage using the US Navy circumference method

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Body fat percentage — Quick answer

Body fat percentage is the fraction of total body mass that is fat (vs lean tissue, bone, water). Several formulas estimate it from circumference measurements.

U.S. Navy (men): BF% = 86.010 × log10(waist−neck) − 70.041 × log10(height) + 36.76
U.S. Navy (women): BF% = 163.205 × log10(waist+hip−neck) − 97.684 × log10(height) − 78.387

Worked example: Male, height 175 cm, neck 38 cm, waist 90 cm. BF% = 86.010 × log10(52) − 70.041 × log10(175) + 36.76 = 86.010 × 1.716 − 70.041 × 2.243 + 36.76 = 27.2 %.

Body fat % health classification (American Council on Exercise)

CategoryMenWomen
Essential fat2–5 %10–13 %
Athletes6–13 %14–20 %
Fitness14–17 %21–24 %
Average18–24 %25–31 %
Obese≥ 25 %≥ 32 %

Standard / source: U.S. Navy circumference method (Hodgdon & Beckett, 1984); American Council on Exercise (ACE) classification ranges.

Used for: Fitness assessment, sports performance tracking, weight-loss goal setting, body composition monitoring without DEXA scan access.

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Formula

This calculator uses the standard body fat calculator formula:

US Navy Method (men)
BF% = 495/(1.0324−0.19077×log(waist−neck)+0.15456×log(height))−450

Frequently Asked Questions

What is the US Navy body fat method? ⌄

The US Navy method estimates body fat percentage from body circumference measurements (neck, waist, and for women, hips) using logarithmic equations developed for military fitness standards.

What is a healthy body fat percentage for men? ⌄

For men: 6–13% is athletic, 14–17% is fit, 18–24% is acceptable, and above 25% is considered obese. These vary slightly by source.

What is a healthy body fat percentage for women? ⌄

For women: 16–20% is athletic, 21–24% is fit, 25–31% is acceptable, and above 32% is considered obese.

Is the Navy method accurate? ⌄

The US Navy method has an error margin of ±3–4% compared to DEXA scans. It is a reasonable estimate for general health tracking but less accurate than clinical methods.

How do I measure my waist for body fat? ⌄

Measure around the abdomen at the level of the navel (for men) or at the narrowest point (for women). Stand upright and measure after exhaling normally.

Does muscle mass affect body fat measurement? ⌄

The Navy method estimates fat indirectly through circumference measurements, which can be affected by both fat and muscle distribution. Very muscular individuals may get slightly inaccurate results.

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Standards & method

✓ Independently verified 12 July 2026
Governing standard
US Navy circumference method · Jackson & Pollock skinfold equations
Clauses applied
The US Navy method uses neck, waist (and hip, for women) circumferences plus height. Jackson & Pollock (1978, 1980) use skinfold thicknesses.
Core formula
Navy (men): %BF = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
Why this matters
These are regression estimates with an error of roughly ±3–4 percentage points, and they lose accuracy at the extremes of body composition. DEXA is the reference method. This is general information, not medical advice — discuss any health decision with a qualified clinician.
Independently verified
12 July 2026 — Re-derived from the governing standard and checked numerically against worked reference cases from the standard itself — not merely tested for “returns a number”.

Results are for guidance. Verify against the current edition of the governing standard and have a qualified professional review before use in practice.