Body Fat Percentage Calculator
Estimate your body fat percentage using simple tape measurements of your waist, neck, and height — no calipers or lab equipment needed. Based on the U.S. Navy circumference method, useful for fitness tracking and health assessments.
About this calculator
This calculator uses the U.S. Navy Body Fat Formula, developed for quick field assessment without specialized equipment. For men, the equation is: Body Fat % = 495 / (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450. The formula was derived by regression analysis correlating circumference measurements with underwater weighing results. The waist and neck measurements capture abdominal and upper-body fat distribution, while height normalizes the result for body size. Measurements must be taken at specific anatomical sites — the waist at the navel level and the neck just below the larynx — for accuracy. The method has a reported error margin of ±3–4 percentage points compared to DEXA scans, making it a practical but approximate estimate.
How to use
Example (male): waist = 90 cm, neck = 38 cm, height = 178 cm. Step 1: waist − neck = 90 − 38 = 52. Step 2: log₁₀(52) ≈ 1.7160; log₁₀(178) ≈ 2.2504. Step 3: Denominator = 1.0324 − (0.19077 × 1.7160) + (0.15456 × 2.2504) = 1.0324 − 0.3274 + 0.3477 = 1.0527. Step 4: 495 / 1.0527 ≈ 470.2. Step 5: 470.2 − 450 = 20.2% body fat. This falls within the 'fitness' category for adult men.
Frequently asked questions
How accurate is the U.S. Navy body fat formula compared to DEXA scanning?
The U.S. Navy formula typically estimates body fat within 3–4 percentage points of DEXA (dual-energy X-ray absorptiometry), which is considered the gold standard. Studies show it performs best for individuals with average body proportions and becomes less reliable at the extremes of very high or very low body fat. It also assumes typical fat distribution patterns, so individuals who carry fat disproportionately in areas not measured may get less accurate results. For most fitness tracking purposes, its consistency over time makes it a useful monitoring tool even if the absolute number is approximate.
What body fat percentage is considered healthy for men and women?
For men, healthy body fat is generally considered to fall between 10–20%, with athletes often in the 6–13% range and obesity defined above 25%. For women, healthy ranges are higher due to essential fat needed for hormonal function, typically 20–30%, with athletes at 14–20% and obesity above 32%. These ranges come from the American Council on Exercise (ACE) classification system. Age also influences healthy ranges, as body fat naturally increases slightly with age even when weight stays stable.
How should I measure my waist and neck for the most accurate body fat result?
For the waist, measure horizontally at the level of the navel while relaxed — do not suck in or flex your abdomen. For the neck, measure just below the larynx (Adam's apple), keeping the tape perpendicular to the neck's long axis. Use a soft, non-elastic measuring tape and take each measurement twice, averaging the results if they differ. Consistent measurement technique matters more than absolute precision, especially when tracking changes over weeks or months.