📏 Body Fat Calculator
Estimate your body fat percentage.
What is this tool?
The Body Fat Calculator uses the U.S. Navy circumference method to estimate body fat percentage from simple body measurements. Unlike BMI, which only compares weight to height, body fat percentage reveals the actual proportion of fat versus lean mass (muscle, bone, organs, and water) in your body. This makes it a far more meaningful indicator of metabolic health, fitness progress, and nutritional status. The U.S. Navy method, developed from anthropometric data on thousands of military personnel, was designed to replace costly or impractical lab tests. For men, it uses height, neck, and waist measurements; for women, it adds a hip measurement. While not as precise as clinical methods such as DEXA scans or underwater weighing, the Navy method is free, fast, and accurate enough for most people to track changes over time. Understanding your body fat percentage helps you set realistic fitness goals, estimate calorie needs more precisely, and identify whether weight changes reflect fat loss or muscle gain.How it works
U.S. Navy method (metric, cm): For men, body density = 1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height); body fat % = (495 / body density) − 450. For women, replace waist − neck with waist + hip − neck. Example: a man with a 85 cm waist, 38 cm neck, and 178 cm height has a body fat percentage of approximately 18%. Always measure at the narrowest and widest natural points.How to use
- Select your biological sex — the formulas differ because men and women store fat differently.
- Enter your height.
- Measure your neck at its narrowest point, just below the larynx.
- Measure your waist at the navel (men) or natural waist (women), keeping the tape level and relaxed.
- Women should also measure the hips at the widest point.
- Click Calculate to see your estimated body fat percentage and category. Measure after exhaling, without pulling the tape tight, and use a flexible tape for consistency.
Reference Table
| Category | Body Fat % – Men | Body Fat % – Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25% and above | 32% and above |
Frequently Asked Questions
Frequently Asked Questions
How accurate is the Navy body fat method compared to DEXA?
The Navy method typically agrees with DEXA scans within about 3–4 percentage points when measurements are taken correctly. It is not as precise as clinical methods, but it is free, repeatable, and excellent for tracking trends over weeks and months. Consistency in how and when you measure matters more than hitting an exact number.
What is essential fat, and why do women need more?
Essential fat is the minimum fat required for normal physiological functions, including hormone production, vitamin absorption, and cell membrane health. Women naturally carry more essential fat (10–13%) than men (2–5%) due to reproductive and hormonal needs. Dropping below these levels can disrupt menstruation and overall health.
What is a healthy body fat range?
For most adults, a healthy range is 14–24% for men and 21–31% for women. Athletes often sit lower, while very lean fitness enthusiasts may reach 10–13% (men) or 14–20% (women). Going below essential fat levels is dangerous, and levels above the average range increase risk for metabolic and cardiovascular conditions.
How often should I measure my body fat?
Every two to four weeks is ideal. Body fat changes slowly, so measuring too frequently leads to frustration from normal daily fluctuations in hydration and digestion. Measure at the same time of day, ideally in the morning, using the same method each time.