Body fat percentage calculator
Estimate your body fat percentage using the US Navy tape measurement method. No gym equipment needed.
Measure at the navel (men) or narrowest point (women)
Measure at the widest point
Related tools
About the US Navy method
The US Navy tape method estimates body fat percentage using simple circumference measurements. For men, it uses neck and waist measurements. For women, it uses neck, waist, and hip measurements. It is less accurate than methods such as DEXA or hydrostatic weighing, but it is popular because it requires only a tape measure and can be repeated easily at home.
Results depend heavily on measurement quality. For better consistency, measure at the same time of day, use a flexible tape measure, and keep the tape snug without compressing the skin. It also helps to take each measurement twice and average the results.
Formula
Men: BF% = 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76
Women: BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Frequently asked questions
What is a healthy body fat percentage?
According to the American Council on Exercise (ACE), healthy body fat ranges are 18–24% for men and 25–31% for women. Athletes typically fall in the 6–13% range for men and 14–20% for women. Essential fat — the minimum needed for basic physiological functions — is 2–5% for men and 10–13% for women. Going below essential fat levels is dangerous.
How accurate is the US Navy tape method?
The US Navy method has an error margin of roughly ±3–4 percentage points compared to DEXA scanning, which is considered the gold standard. It is more accurate than BMI for estimating body composition but less precise than skinfold callipers, hydrostatic weighing, or bioelectrical impedance analysis (BIA). It works best as a tracking tool to monitor trends over time rather than for absolute accuracy.
Where exactly should I measure my waist?
For men, measure the waist at the level of the navel (belly button), at the end of a normal exhale. For women, measure at the narrowest point of the torso, usually just above the navel. Do not suck in your stomach. Consistent measurement technique matters more than absolute accuracy — always measure at the same point to track changes reliably.
Can body fat percentage be lower than BMI suggests?
Yes, this is common in athletes and people with high muscle mass. A muscular person may have a BMI in the overweight range but a body fat percentage in the athlete or fitness category. This is one reason body fat percentage is a more informative measure of health risk than BMI alone, especially for people who exercise regularly.
What is lean mass and why does it matter?
Lean mass is everything in your body that is not fat — muscles, bones, organs, water, and connective tissue. It is metabolically active, meaning it burns more calories at rest than fat tissue. Preserving lean mass during weight loss is important to keep your metabolism from slowing down too much. High protein intake and resistance training are the most effective ways to protect lean mass during a deficit.
How often should I measure my body fat?
Once every 4–6 weeks is sufficient for most people. Body fat changes slowly — weekly measurements often show noise rather than real change. For the most consistent results, always measure at the same time of day (ideally morning, before eating), with the same tool, and by the same person. Hydration levels and bloating can affect circumference measurements significantly.
Related articles
Is BMI Accurate for Athletes? Why the Number Often Misses the PointAthletes often get BMI results that seem misleading because muscle changes the picture. This guide explains whether BMI is accurate for athletes and why body-fat context usually matters more.
BMI for Women vs Men: What Changes, What Doesn’t, and What to WatchBMI uses the same formula for women and men, but body composition differences still matter. This guide explains how BMI applies across sexes and where body-fat context becomes more useful.
Is BMI Accurate for Most People? What It Tells You and What It MissesBMI is one of the most widely used health screening metrics, but it has clear limits. This guide explains how accurate BMI really is, when it helps, and when other measures matter more.