Body Fat Calculator — U.S. Navy & Skinfold Methods
Estimate your body fat percentage with a tape measure (U.S. Navy method) or skinfold calipers (Jackson-Pollock 3-site), compare it with a BMI-based estimate, and see your fat mass, lean mass and body-fat category.
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Body fat % × weight
Everything that isn't fat
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Deurenberg formula (BMI, age, sex)
Body Fat Categories (American Council on Exercise)
General reference ranges for adults. Healthy ranges also rise somewhat with age.
| Category | Men | Women |
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How this calculator works
The U.S. Navy method estimates body fat from circumference measurements using a logarithmic formula, and is a widely used field method that doesn't require calipers or special equipment.
- Navy — men (cm): 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450
- Navy — women (cm): 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
- Jackson-Pollock 3-site: body density from the sum of three skinfolds and age (men: chest, abdomen, thigh; women: triceps, suprailiac, thigh), converted to body fat with the Siri equation: 495 ÷ density − 450.
- Deurenberg (BMI-based): 1.20 × BMI + 0.23 × age − 10.8 × sex (1 = male, 0 = female) − 5.4. A rough population estimate, shown for comparison only.
By Suhaib Hassan · Reviewed 28 September 2026 against the original published equations · How CalculatePilot verifies formulas →
How to make repeat measurements more useful
- Use the same measurement method and locations each time.
- Measure under similar conditions, such as a similar time of day.
- Keep the tape snug without compressing the skin.
- Repeat measurements when practical and look at the trend rather than one isolated percentage.
Consistent technique makes changes over time easier to interpret, even though the absolute percentage remains an estimate.
Accuracy of this method
The Navy method can be useful for consistent at-home tracking, but the size and direction of its error vary between people and it should not be presented as interchangeable with DEXA. Skinfold results also depend heavily on measurement technique and operator skill.
Comparing measurement methods
Besides the Navy circumference and skinfold methods used here, other common body fat estimation methods include bioelectrical impedance scales and DEXA scans. DEXA is generally considered the most accurate but requires specialized equipment, while circumference and caliper methods offer a reasonable free or low-cost alternative.
For tracking progress over time, consistency in measurement method and technique matters more than absolute accuracy — comparing this month's Navy method result to last month's using the same technique is more meaningful than comparing to a one-time DEXA scan result.
A worked example
A man with a 90 cm waist, 38 cm neck, and 178 cm height: using the Navy formula, this works out to about 20% body fat, in the "average" ACE category.
If his waist measured 100 cm instead (all else equal), the estimate rises to about 27% — illustrating how sensitive this method is to waist measurement specifically, making consistent, careful measurement technique important for tracking change over time.
Once you have a body fat estimate, our Lean Body Mass Calculator and the lean-mass formulas in the TDEE Calculator can use it. Medical information, not medical advice.
Sources
- U.S. Navy Body Composition Assessment guidance
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984.
- Jackson AS, Pollock ML. Generalized equations for predicting body density of men. Br J Nutr 1978;40:497–504. Jackson AS, Pollock ML, Ward A. Generalized equations for predicting body density of women. Med Sci Sports Exerc 1980;12:175–181.
- Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness. Br J Nutr 1991;65:105–114.
- American Council on Exercise — body fat percentage categories.
Frequently asked questions
How accurate is the U.S. Navy body fat method?
It is a field estimate and measurement error can be meaningful. Accuracy varies with body composition, measurement technique and the method used; it should not be treated as equivalent to a clinical body-composition measurement.
Why does the formula differ for men and women?
Body fat distribution patterns differ by sex, so the formula includes hip measurement for women to account for typical fat distribution differences.
What is a healthy body fat percentage?
Reference ranges for body fat vary by age, sex, population and source. These categories are educational reference points, not personalized medical targets or diagnoses.
How often should I re-measure my body fat?
Monthly is a reasonable cadence for tracking meaningful change — body fat percentage doesn't shift dramatically week to week, so frequent measurement mostly captures measurement noise rather than real change.
How does the Navy method compare to a DEXA scan?
DEXA and circumference methods use different measurement approaches. A DEXA result should not be treated as a simple conversion or guaranteed ground truth for an individual; the Navy result is best used as a consistent field estimate.
Where exactly should I measure my waist and neck?
Waist is typically measured at the navel level, and neck just below the larynx — consistent placement each time you measure matters more than the exact spot, for tracking change over time.
Tape measure or skinfold calipers — which is better?
Both are estimates. Skinfolds taken by a trained person can be quite accurate, but results vary a lot with technique; the tape method is easier to repeat consistently at home. Pick one and use it the same way each time.
Next Steps
Use your body-fat estimate in other calculators.