Body Fat Calculator (Navy Method)
Estimates body fat percentage from circumference measurements using the US Navy formula. Validated against hydrostatic weighing and accessible without specialist equipment.
Your Measurements
Measure below the larynx, slightly downward slope.
Males: at the navel. Females: at the narrowest point.
At the widest point across the hips.
Your Result
Enter your measurements to estimate body fat percentage.
📋 What Your Result Means
For educational purposes only — not medical advice.
The gauge above shows where your result sits. The table below uses ACSM (American College of Sports Medicine) body fat classification ranges.
| Category | Males | Females |
|---|---|---|
| Essential Fat | 2 – 5% | 10 – 13% |
| Athletes | 6 – 13% | 14 – 20% |
| Fitness | 14 – 17% | 21 – 24% |
| Acceptable | 18 – 24% | 25 – 31% |
| Obese | > 25% | > 32% |
Essential fat is the minimum needed for normal hormonal, neurological, and organ function. Dropping below this range (2-5% for males, 10-13% for females) is physiologically dangerous and unsustainable. Competition bodybuilders only reach these levels briefly for stage day.
Accuracy of the Navy method: The circumference-based Navy formula has a standard error of estimate (SEE) of approximately 3-4% compared to DEXA or hydrostatic weighing. This means your true body fat could be 3-4 percentage points higher or lower than what is shown. For most people this is adequate for tracking progress over time, even if the absolute number is imprecise.
Consistency matters more than accuracy. Measure at the same time of day (morning, fasted), at the same anatomical landmarks, using the same tape tension. Small changes in measurement technique produce larger errors than the formula itself. Track your trend over weeks and months rather than fixating on a single reading.
Females: 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hips − neck) + 0.22100 × log₁₀(height)) − 450
Limitations
Accuracy depends on precise measurement technique. Standard error is approximately ±3–4%, which is acceptable for tracking trends but not as precise as DEXA or underwater weighing. Results may be less accurate for very lean or very obese individuals.
~ Moderate EvidenceWant to learn more? Read our in-depth article: How to Measure Body Fat at Home: The Navy Method →
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