Body Fat Calculator - US Navy Method & Body Composition
Estimate body fat percentage using the US Navy circumference method. Enter waist, neck, and height - plus hip for women - to see body fat category and lean vs fat mass.
Body Measurements
US Navy method using waist, neck, and height.
Body Fat Estimate
Body Fat Percentage
17.5%
Fitness
Methodology and limitations
Last reviewed:
Methodology
Estimates body fat percentage using the U.S. Navy circumference method from height, waist, neck, and hip (women) measurements, then classifies the result into common body-fat categories.
Limitations
Circumference methods are estimates and depend on correct tape placement. They may be less accurate for very lean or very high body-fat individuals compared to DEXA or hydrostatic weighing.
Official sources
How Body Fat Percentage Is Estimated
Estimate body fat percentage using the US Navy circumference method. Enter waist, neck, and height - plus hip for women - to see body fat category and lean vs fat mass.
Method used
The calculator applies the U.S. Navy circumference formula using height, waist, and neck measurements (plus hip for women), converts the result to a body-fat percentage, and assigns a descriptive category.
Male %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76 (Navy method)
Practical example
A man who is 70 inches tall with a 34-inch waist and 15-inch neck might estimate body fat near 18%, classified in the fitness range on the calculator scale.
- Sex, height, waist circumference, neck circumference
- Hip circumference for women
- Imperial or metric measurements
The result shows body-fat percentage, category label, and estimated lean mass and fat mass in pounds.
Assumptions
- Measurements are taken at consistent anatomical landmarks.
- Waist must be larger than neck for a valid result.
- The Navy method is an estimate, not a clinical measurement.
What this includes
- Body-fat percentage, category, lean mass estimate, and fat mass estimate.
What this excludes
- DEXA scans, Bod Pod, hydrostatic weighing, bioimpedance devices, and body-composition prescriptions from a clinician.
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Frequently Asked Questions
How does the US Navy body fat method work?
The US Navy method uses circumference measurements and height in logarithmic formulas developed for military fitness assessments. It estimates body fat percentage without calipers, DEXA, or underwater weighing. Enter waist, neck, and height—plus hips for women—to see estimated body fat, category, and lean versus fat mass. Treat outputs as screening estimates for trends, not clinical diagnoses.
How should I measure waist and neck?
Measure waist at navel level after a normal exhale, not after sucking in. Measure neck just below the larynx with the tape snug but not compressing skin. Measure at the same time of day when possible, because food, training, and sodium can change circumference. Consistency between sessions matters more than squeezing the tape tighter for a lower reading.
Why do women need a hip measurement?
The female Navy formula accounts for hip circumference because typical fat distribution differs by sex and hips improve the circumference model for women. Men use waist and neck only with height. Measure hips at the widest point of the buttocks with feet together. Skipping hips for women produces an incomplete input and an unreliable educational estimate.
How accurate is this compared to DEXA?
Circumference methods typically have a few percentage points of error versus DEXA scans and can be affected by measurement technique. Use results for tracking trends over weeks with the same tape method rather than as a clinical diagnosis. If you need precise body composition for medical or performance decisions, ask a clinician about laboratory or imaging options.
What body fat ranges are considered healthy?
Published fitness ranges are often cited around 14–17% for men and 21–24% for women, with essential fat minimums lower and athlete ranges varying widely. Age, sex, and sport matter, and category labels are not medical diagnoses. Compare your estimate to your own baseline over time, and discuss concerning changes or symptoms with a healthcare professional.