Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method — the most accurate approach without specialized equipment. Just a tape measure is all you need.
Stand straight against a wall, without shoes
Measure around the narrowest point of your neck
Measure at navel level, relaxed (don't suck in)
Measure at the widest point of your hips/buttocks
Needed to calculate fat mass and lean mass
Your Estimated Body Fat
Body Composition Breakdown
Fat Mass
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Lean Mass
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How You Compare
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What Is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that is made up of fat tissue. Unlike BMI, which only considers height and weight, body fat percentage gives a much clearer picture of your actual body composition and health status.
Your body needs a certain amount of essential fat to function properly — protecting organs, regulating temperature, and producing hormones. Beyond essential fat, your body stores additional fat as energy reserves. The balance between fat and lean mass (muscle, bone, organs, water) determines your body composition.
Two people with the same BMI can have very different body fat percentages. An athlete with significant muscle mass may be "overweight" by BMI but have a low, healthy body fat percentage. That's why body fat % is a superior metric for assessing fitness and health.
The US Navy Method Explained
The US Navy method was developed by Hodgdon and Beckett at the Naval Health Research Center. It uses circumference measurements of the neck, waist, and hips (for women) along with height to estimate body fat percentage. Research shows it correlates well with hydrostatic weighing, the gold standard.
Formulas Used:
Male
BF% = 495 / (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450
Female
BF% = 495 / (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.22100 × log10(height)) - 450
All measurements must be in centimeters for the formulas. Our calculator handles unit conversion automatically if you use inches.
Body Fat Percentage Categories
Body fat ranges differ significantly between men and women due to biological differences. Women naturally carry more essential fat for reproductive and hormonal functions.
Male
| Category | Body Fat % |
|---|---|
| Essential Fat | 2 – 5% |
| Athletes | 6 – 13% |
| Fitness | 14 – 17% |
| Average | 18 – 24% |
| Obese | 25%+ |
Female
| Category | Body Fat % |
|---|---|
| Essential Fat | 10 – 13% |
| Athletes | 14 – 20% |
| Fitness | 21 – 24% |
| Average | 25 – 31% |
| Obese | 32%+ |
How to Measure Accurately
Accurate measurements are essential for reliable results. Follow these guidelines:
Neck
Wrap the tape just below the larynx (Adam's apple). Measure at the narrowest point. Keep the tape level and snug but not tight. Look straight ahead.
Waist
Measure at your navel (belly button) level. Stand relaxed — do not suck in your stomach. Keep the tape horizontal and snug. Measure after exhaling normally.
Hips (Women Only)
Measure at the widest point of your hips and buttocks. Stand with feet together. Keep the tape horizontal all the way around.
General Tips
Measure in the morning before eating. Use a non-stretch tape. Take each measurement 2–3 times and average. Measure on bare skin. Stand upright and relaxed.
Limitations
Estimation only — The US Navy method provides an estimate, not a precise measurement. For clinical accuracy, consider DEXA scans, hydrostatic weighing, or BodPod.
Not for everyone — May be less accurate for highly muscular individuals, very lean athletes, people with unusual body proportions, or those under 18 or over 70.
Measurement error — Small errors in tape measurements can lead to meaningful differences in the result. Consistency in how and when you measure is important.
Typical accuracy — The US Navy method has an estimated error margin of 3–4%. Use it as a guide and track trends over time rather than focusing on a single number.