Body Fat Percentage Calculator
Your body fat percentage — the proportion of your total weight that is fat tissue — is one of the best indicators of overall fitness and metabolic health. Unlike BMI, which uses only height and weight, body fat percentage distinguishes between lean mass (muscle, bone, organs) and fat mass, giving you a much clearer picture of your body composition. This calculator provides two estimation methods side by side: the **U.S. Navy circumference method** (using simple tape-measure readings) and a **BMI-based estimation** (faster but less accurate). Comparing the two helps you assess how reliable each estimate is for your body type.
Your Measurements
Measure below Adam's apple
Measure at navel
Example Use Cases
A 25-year-old male, 183 cm, 82 kg, waist 80 cm, neck 38 cm: Navy method gives 13.8%, BMI method gives 17.2%. The Navy method is likely more accurate here — the BMI method overestimates because it doesn't know this person has above-average muscle.
A 40-year-old female, 165 cm, 68 kg, waist 78 cm, neck 32 cm, hip 102 cm: Navy method gives 28.6%, BMI method gives 29.1%. Close agreement suggests both estimates are in the right ballpark.
How to Interpret Your Results
When the two methods agree within 2–3 percentage points, you can be reasonably confident in the estimate. When they diverge significantly, the Navy method is usually more accurate because it captures fat distribution, whereas the BMI method assumes an average build.
Frequently Asked Questions
Methodology & Limitations
Formulas Used
**Navy Method (Men):** BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76. **Navy Method (Women):** BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387. **BMI Method (Men):** BF% = 1.20 × BMI + 0.23 × age − 16.2. **BMI Method (Women):** BF% = 1.20 × BMI + 0.23 × age − 5.4.
Page-Specific Notes
Both the Navy circumference method and the BMI-based estimation are displayed side by side so users can compare and assess which is more reliable for their body type.
Limitations
Circumference-based estimates have a standard error of ±3–4%. Results are less reliable for individuals with unusual fat distribution patterns, very lean athletes, or the elderly. For clinical accuracy, consider DEXA scanning.
Sources & Citations
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, Report No. 84-29. 1984.
- Deurenberg P, et al. Body mass index as a measure of body fatness. Br J Nutr. 1991;65(2):105-114.
Medical Disclaimer: This calculator provides estimates based on published formulas and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your diet or exercise routine.
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