Know Your True Body Composition
Estimate your body fat percentage with the U.S. Navy circumference method — just a tape measure, no calipers or smart scale required.
Your Results
Three Measurements, One Accurate Estimate
No special equipment needed — just a flexible tape measure and a couple of minutes.
Take Your Measurements
Measure your neck, waist, and (if you're a woman) your hips in inches or centimeters using a soft tape measure.
Enter Your Details
Choose your unit system and gender, then enter your height, weight, and circumference measurements above.
Get Your Results
Instantly see your estimated body fat percentage, fat mass, lean mass, and which category you fall into.
What Is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that is made up of fat tissue, as opposed to lean mass — muscle, bone, organs, and water. Two people can weigh exactly the same on a scale and have very different body compositions.
Unlike body weight or BMI, body fat percentage tells you what your weight is actually made of, which is why it's a far more useful number for tracking fitness progress, health risk, and athletic performance.
Why Track Body Fat Instead of Just Weight
Weight Alone Can Be Misleading
Muscle is denser than fat, so someone who builds muscle while losing fat may see little change on the scale despite a real body composition improvement.
It's Linked to Health Risk
Excess body fat, especially around the abdomen, is associated with higher risk of heart disease, type 2 diabetes, and other metabolic conditions.
It Tracks Real Progress
Body fat percentage shows whether a diet or training program is actually changing your composition, not just your total mass.
How the U.S. Navy Method Works
Developed by Hodgdon & Beckett in 1984 for the U.S. Navy, this method estimates body density from a few circumference measurements, then converts that density into a body fat percentage using the Siri equation.
Body Density (Male)
495 ÷ density − 450, where density = 1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)
Uses neck & waistBody Density (Female)
495 ÷ density − 450, where density = 1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)
Uses neck, waist & hipWhere to Measure
Pull the tape snug but not tight, and measure without compressing the skin.
Swipe to see all columns →
| Measurement | Where | Tip |
|---|---|---|
| Neck | Just below the larynx (Adam's apple), sloping slightly downward toward the front | Don't tilt your head while measuring |
| Waist | At the navel, for both men and women | Measure after a normal exhale, standing relaxed |
| Hip (women only) | At the widest point of the hips/buttocks | Keep feet together and tape level |
| Height | Standing fully upright, without shoes | Measure against a wall for accuracy |
What Counts as a Healthy Body Fat Percentage?
Healthy ranges differ by gender because women naturally carry more essential fat for hormonal and reproductive function.
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
What Raises Body Fat
What Lowers Body Fat
Why Body Fat Differs Between Men and Women
Biology gives women a higher essential fat requirement — that's a healthy difference, not a flaw in the formula.
Women
Men
How Does This Compare to Other Methods?
Every body fat method trades off cost, convenience, and precision. The Navy method sits in a strong sweet spot for a free, at-home estimate.
Navy Method
Smart Scale (BIA)
Skinfold Calipers
DEXA Scan
Tips for a More Accurate Measurement
Use a Cloth Tape
A flexible cloth or vinyl tape measure conforms to your body better than a rigid metal one.
Measure at the Same Time
Body size fluctuates throughout the day — measure first thing in the morning for consistency.
Don't Compress the Skin
The tape should sit snugly against the skin without pinching or pulling it tight.
Take Two or Three Readings
Measure each spot a couple of times and average the results to reduce error.
8 Ways to Lower Your Body Fat Percentage
Sustainable fat loss comes from a handful of consistent habits, not extreme short-term measures.
Run a Moderate Calorie Deficit
Aim for roughly 300–500 calories below maintenance — large enough to lose fat, small enough to preserve muscle.
Prioritize Protein
Around 0.7–1g of protein per pound of bodyweight helps preserve lean mass while in a deficit.
Strength Train Regularly
Resistance training signals your body to keep muscle even as you lose fat, improving body composition.
Increase Daily Movement
Walking and everyday activity (NEAT) burn meaningful calories without adding training fatigue.
Sleep 7–9 Hours
Poor sleep raises hunger hormones and makes fat loss noticeably harder, even with a good diet.
Limit Added Sugar & Alcohol
Both are easy sources of excess calories that add up quickly without much satiety.
Track Progress with More Than the Scale
Re-measure your circumferences every few weeks — body fat % often improves before total weight does.
Be Patient and Consistent
Healthy fat loss is typically 0.5–1% of bodyweight per week — small, steady changes that actually stick.
Common Questions
Everything you need to know about measuring and improving your body fat percentage.