Quick Examples
📏 Body Fat Calculator
Age (years)
Height (cm)
Weight (kg)
Enter your details and click Calculate
How It Works
Body Fat Formulas & Worked Examples
US Navy Method (Circumference-Based)
Men: 495 / (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450
Women: 495 / (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450
Example: Man, neck 38cm, waist 88cm, height 175cm → approximately 19% body fat.
Deurenberg BMI-Based Formula
BF% = (1.20 × BMI) + (0.23 × Age) − (10.8 × sex) − 5.4
sex = 1 for male, 0 for female
Example: Man, BMI 26.1, age 30 → (1.2×26.1) + (0.23×30) − 10.8 − 5.4 = 22% body fat.
Reference
Body Fat Percentage Categories
| Category | Women | Men |
|---|---|---|
| Essential Fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32%+ | 25%+ |
Source: American Council on Exercise (ACE) body fat categorization.
Background
Factors That Affect Measurement Accuracy
- Measurement technique — inconsistent tape placement or tension skews results
- Hydration & food intake — bloating or dehydration can shift waist measurements
- Muscularity — very muscular individuals may be underestimated by BMI-based formulas
- Time of day — measuring at the same time (e.g. morning) improves consistency
- Body fat distribution — genetics affect where fat is stored, which circumference methods can't fully capture
- Method used — circumference and BMI-based formulas are estimates, not diagnostic measurements
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Sources
Scientific References
- Hodgdon JA, Beckett MB. "Prediction of Percent Body Fat for U.S. Navy Men and Women." Naval Health Research Center, 1984.
- Deurenberg P, Weststrate JA, Seidell JC. "Body mass index as a measure of body fatness: age- and sex-specific prediction formulas." British Journal of Nutrition, 1991.
- American Council on Exercise (ACE). "Body Fat Percentage Norms."
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