Body Fat Calculator
Free online body fat calculator. Estimate your body fat percentage using standard US Navy or tape measure methods.
Body fat
19.5%
Fitness
Method
How this calculator works
The U.S. Navy formula uses logarithmic equations with circumference measurements relative to height to estimate body fat percentage.
Male: BF% = 495 / (1.0324 − 0.19077×log₁₀(waist−neck)
+ 0.15456×log₁₀(height)) − 450
Female: BF% = 495 / (1.29579 − 0.35004×log₁₀(waist+hip−neck)
+ 0.22100×log₁₀(height)) − 450
All measurements in centimeters.- Select your gender.
- Enter your height in cm.
- Measure and enter neck circumference at the narrowest point.
- Measure and enter waist circumference at navel level.
- For women: measure and enter hip circumference at the widest point.
- The calculator applies the Navy formula and classifies your body fat category.
Examples
Worked examples
Real numbers, end-to-end results.
Male · 175cm · Neck 38cm · Waist 85cm
~19.5% · Fitness
Typical fit male — within healthy range.
Female · 165cm · Neck 32cm · Waist 70cm · Hip 95cm
~25% · Fitness
Healthy female range.
Male · 180cm · Neck 42cm · Waist 100cm
~24% · Average
Approaching overweight threshold.
Use cases
When to use it
- Track body composition changes during fitness programs.
- Get a more meaningful metric than BMI alone.
- Set realistic fat-loss or muscle-gain targets.
- Military and fitness professionals assessing body standards.
Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health.
Sources: Formulas sourced from WHO BMI classifications, Mifflin-St Jeor equation (1990), Harris-Benedict equation, and NIH/CDC published guidelines. Not intended for clinical diagnosis.
FAQ
Frequently asked questions
What is a healthy body fat percentage?
How accurate is the tape measure method?
Why do women naturally have higher body fat?
Where should I measure my waist?
Can I spot-reduce body fat?
Methodology, assumptions & limitations
How we calculate: This calculator uses standard, peer-reviewed mathematical formulas implemented in TypeScript. All calculations run entirely in your browser — no data is sent to any server.
Assumptions: Unless stated otherwise, calculations assume constant rates over the specified period, no taxes or fees beyond those explicitly input, and standard compounding conventions for the formula type.
Limitations: Results are estimates for planning purposes. Real-world outcomes may differ due to variable rates, regulatory changes, taxes, fees, inflation, or other factors not modeled. This tool does not constitute medical advice or clinical diagnosis.
When NOT to use this: Do not rely solely on this calculator for medical decisions or diagnoses — always consult a qualified healthcare provider.
Feedback: Found an error or have a suggestion? Contact us — we review and correct reported issues within 48 hours.
Deep Dive Guide
Body Fat Guide
Comprehensive guide for body fat.
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