US Navy Body Fat & Composition Calculator
Calculate body composition and body fat percentage using the official U.S. Navy circumference-based equations. Check your ACE fitness category in real-time.
📏 Biological Metrics
📊 Body Composition Results
About the US Navy Circumference Method
How is it Calculated?
The US Navy formula estimates body fat using mathematical models based on height and body circumferences. For men, the formula measures the neck and waist. For women, it measures the neck, waist, and hips. All measurements must be taken with a non-stretch tape measure.
Navy Equations (Metric)
Men:
BF% = 495 / (1.0324 - 0.19077 * log10(waist - neck) + 0.15456 * log10(height)) - 450
Women:
BF% = 495 / (1.29579 - 0.35004 * log10(waist + hip - neck) + 0.22100 * log10(height)) - 450
How to Take Accurate Measurements
Neck: Wrap just below the larynx, pulling slightly downward in front.
Waist: Measure horizontally around the navel for men, or at the natural narrowest waistline for women.
Hips: (Women only) Measure horizontally around the widest part of the glutes.
A Worked Example
Take a man 70 inches tall with a 15-inch neck and a 34-inch waist. The Navy equation subtracts neck from waist (19 inches), runs both that figure and his height through a logarithmic formula, and returns a body-fat estimate of about 17.5% — squarely in the "fitness" range.
A single inch added at the waist pushes the result up by nearly two percentage points, which is why a snug, consistent tape placement matters far more than the exact spot you measure. For tracking progress, always measure at the same time of day under the same conditions.
Frequently Asked Questions
How accurate is the Navy body fat method?
The tape method is typically within about 3–4% of advanced methods like DEXA for most people. It's free and repeatable, but body shape and consistent measuring technique affect accuracy.
What is a healthy body fat percentage?
General fitness ranges are roughly 10–20% for men and 18–28% for women, with athletes lower. Essential fat — below which health suffers — is about 2–5% for men and 10–13% for women.
How is body fat different from BMI?
BMI uses only height and weight and can misjudge muscular bodies, while the Navy method estimates actual fat from body circumferences, giving a clearer picture of composition.