How accurate is the Navy method?

It's typically within a few percentage points of more precise methods like DEXA scans for most people, though accuracy can drop for very lean or very high body-fat individuals. It's best used to track your own trend over time rather than as an exact number.

Where exactly should I measure?

Waist is measured at the navel, neck just below the larynx, and hip (for women) at the widest point. Measure snugly but without compressing the skin, and measure at the same time of day for consistent tracking.

Why does the formula differ between men and women?

Typical body fat distribution differs between sexes, so the Navy method uses separate validated formulas (and an additional hip measurement for women) to account for that difference.

Should I measure daily to track progress?

Weekly or biweekly measurements, taken consistently at the same time of day and in the same way, tend to give a clearer trend than daily measurements, which can fluctuate slightly from things like hydration and measurement technique.

Is this a substitute for a doctor's assessment?

No — this is a convenient estimation method for personal tracking, not a clinical diagnostic tool. For a medical assessment of body composition or health, consult a healthcare provider.

Health & Fitness Cluster

Body Fat Calculator

Estimate body fat percentage using the U.S. Navy tape-measurement method.

TL;DR: Body Fat Calculator is a free, browser-based tool that lets you estimate body fat percentage using the U.S. Navy tape-measurement method.

Sex

Height (cm)

Neck (cm)

Waist (cm)

About the Body Fat Calculator

The Body Fat Calculator computes health and physiological metrics based on established clinical formulas, helping you monitor fitness benchmarks, body composition, and daily nutritional requirements.

How to Use the Body Fat Calculator

Select your measurement system (Metric or Imperial units).
Enter your height, weight, age, and relevant biometric measurements.
View your calculated biometric score and clinical classification category.
Use the target recommendations to guide sustainable fitness and wellness goals.

Mathematical Formula & Methodology

Here is the standard mathematical equation used to calculate this result accurately:

\text{Men: } \%BF = 86.010 \log_{10}(\text{waist} - \text{neck}) - 70.041 \log_{10}(\text{height}) + 36.76

Formula Variables Explained:
US Navy Body Fat formula using anthropometric circumference measurements to estimate body composition and fat percentage.

Step-by-Step Worked Example

For a male with 34 in waist, 16 in neck, and 70 in height: Body fat percentage is estimated at ~15.2% (Athletic/Fitness range).

Expert Tips for Body Fat Calculator

Track Long-Term Trends: Measure biometrics under consistent conditions (e.g., first thing in the morning) rather than stressing over daily fluctuations.
Holistic Context: Treat formula calculations as broad wellness guidelines rather than strict medical diagnoses.
Consult Professionals: Consult a physician or registered dietitian before making substantial dietary or caloric adjustments.

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100% Client-Side Privacy Guarantee

All processing runs locally inside your browser using JavaScript and HTML5 APIs. Your data, files, and inputs are never uploaded to any remote server. Complete privacy by design.

Frequently Asked Questions

: It's typically within a few percentage points of more precise methods like DEXA scans for most people, though accuracy can drop for very lean or very high body-fat individuals. It's best used to track your own trend over time rather than as an exact number.
: Waist is measured at the navel, neck just below the larynx, and hip (for women) at the widest point. Measure snugly but without compressing the skin, and measure at the same time of day for consistent tracking.
: Typical body fat distribution differs between sexes, so the Navy method uses separate validated formulas (and an additional hip measurement for women) to account for that difference.
: Weekly or biweekly measurements, taken consistently at the same time of day and in the same way, tend to give a clearer trend than daily measurements, which can fluctuate slightly from things like hydration and measurement technique.
: No — this is a convenient estimation method for personal tracking, not a clinical diagnostic tool. For a medical assessment of body composition or health, consult a healthcare provider.

Cite This Tool

Referencing this tool in a paper, article, or bibliography? Copy a ready-made citation below.

NexLove.org. (2026). Body Fat Calculator [Software]. https://nexlove.org/tools/body-fat-calculator.html

“Body Fat Calculator.” NexLove.org, 2026, nexlove.org/tools/body-fat-calculator.html.

NexLove.org (2026) Body Fat Calculator. Available at: https://nexlove.org/tools/body-fat-calculator.html (Accessed: 2026).

@misc{nexlove_body_fat_calculator,
  title = {Body Fat Calculator},
  author = {{NexLove.org}},
  year = {2026},
  url = {https://nexlove.org/tools/body-fat-calculator.html}
}

Embed This Tool

Add the live Body Fat Calculator tool to your own website with this snippet — it loads the real, working tool in an iframe, not a static screenshot.

<iframe src="https://nexlove.org/embed/body-fat-calculator.html" width="100%" height="600" style="border:1px solid #e2e8f0;border-radius:12px" title="Body Fat Calculator — NexLove.org" loading="lazy"></iframe>

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