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Health • Body Fat % (US Navy Method)

Body Fat % (US Navy Method)

Estimate body fat percentage and lean body mass using standard circumference tape measurements.

Unit System:
Estimated Body Fat %
16.4%
Lean Body Mass
66.9 kg
Fat Mass
13.1 kg
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Calculation Guide & Reference

US Navy Body Fat Percentage & Lean Mass Mathematics

Body fat calculator using the US Navy circumference method. Estimate body fat percentage and lean body mass from waist, neck, hip, and height measurements.

Standardized Mathematical Formula
Men: 495 / (1.0324 − 0.19077·log₁₀(waist−neck) + 0.15456·log₁₀(height)) − 450

The US Navy method estimates body fat percentage from simple tape-measure circumferences rather than calipers or scans. It was developed and validated by the US Navy as a low-cost, reasonably accurate field method for fitness assessments.

Variables:
Waist, Neck, Hip:Circumference measurements in centimeters (hip only used for women)
Height:Standing height in centimeters
Women's formula:495 / (1.29579 − 0.35004·log₁₀(waist+hip−neck) + 0.22100·log₁₀(height)) − 450
How It Works (Step-by-Step)
  • 1Select your gender, then enter height, neck, and waist circumference (plus hip circumference for women).
  • 2Enter your total body weight to also see lean mass and fat mass in kilograms.
  • 3View your estimated body fat percentage, lean body mass, and fat mass.
Real-World Numerical Example
A Man, 178cm Tall, 85cm Waist, 38cm Neck, 80kg

A man measures 178 cm tall, an 85 cm waist, and a 38 cm neck, weighing 80 kg total.

•Waist − Neck = 85 − 38 = 47 cm.
•BF% = 495 / (1.0324 − 0.19077×log₁₀(47) + 0.15456×log₁₀(178)) − 450 ≈ 16.4%.
•Fat mass: 80 × 0.164 ≈ 13.1 kg. Lean mass: 80 − 13.1 ≈ 66.9 kg.
Result: Estimated body fat is approximately 16.4%, with about 66.9 kg of lean body mass.
Calculation Best Practices & Tips
Use BMR and TDEE as personalized baselines, then adjust caloric intake by 300-500 kcal/day for sustainable weight management.
Remember that standard BMI does not distinguish between muscle mass and fat mass; athletic individuals should also track body fat percentage and waist-to-height ratios.
Maintain adequate hydration: base intake should generally be 30-35 ml per kilogram of body weight, increasing during intensive exercise.

Frequently Asked Questions (FAQ)

It typically estimates within 3-4 percentage points of more precise methods like DEXA scans, for most body types — accurate enough for tracking progress over time, though not for clinical diagnosis.

Body fat distribution differs by sex — women typically carry more fat around the hips, so the validated female formula incorporates hip circumference to account for that difference in fat distribution pattern.

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