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General estimate for planning only — not medical advice. Consult a doctor about your specific situation.
Calculation details
Adult screening estimate only, not a diagnosis. Body composition, age, pregnancy, medical history, and population-specific risk can change interpretation; discuss health decisions with a qualified clinician.
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What does this calculator estimate?
This calculator estimates your body fat percentage using a standard Navy formula that combines height, neck, waist, and hip measurements in inches. For men it uses waist and neck, and for women it adds hip. Enter your numbers directly in the browser with no signup. Use the result as a general health reference, not a precise medical diagnosis.
How this calculator works
Formula
U.S. Navy circumference method: men %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76; women use waist, neck, and hip terms.
Worked example
A 69-inch person with 15-inch neck, 34-inch waist: about 31% body fat by the Navy method.
Sources
- U.S. Navy — Guide 4 Body Composition Assessment
- CDC — About adult BMI (context and limitations of screening measures)
Sources support the method, terminology, or planning context. Editable assumptions remain your responsibility.
Assumptions to verify
- The named U.S. Navy circumference equations are used with inch measurements.
- Measurements must follow a consistent tape-placement protocol.
- The estimate is not a clinical diagnosis and may be inaccurate for individuals outside the source population.
- This tool provides general estimates for planning and education only; it is not medical advice and not a substitute for a qualified healthcare professional.
- Always consult your doctor or another healthcare provider about your specific situation.
Frequently asked questions
How does the body fat calculator work?
It uses measurements like height, neck, waist, and hip to estimate body fat percentage with established formulas. Just enter your numbers in the browser—no signup required.
Is this body fat calculator accurate?
It provides a close estimate using the U.S. Navy method, ideal for tracking trends over time. For precise clinical results, consult a professional.
Do I need to create an account to use it?
No, the body fat calculator is completely free and browser-based with no signup needed. Simply open the page and input your measurements.
Cite this tool
BoringToolsKit. “Body Fat Estimate Calculator.” boringtoolskit.com/body-fat-calculator/ (reviewed July 2026). Free to reference in articles, syllabi, and answer posts with a link.
Privacy: Inputs and results stay in this browser. Results are planning estimates based on your inputs; verify assumptions and current rules before making decisions.