Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method
How to Use This Body Fat Calculator
- Select your gender (formula differs significantly between men and women)
- Enter your age for age-adjusted ideal body fat ranges
- Enter your height and weight using your preferred units
- Measure your neck circumference at the narrowest point
- Measure your waist at navel level
- Women: also measure hip circumference at the widest point
- Click 'Calculate Body Fat' to see your percentage and body composition
Example: A 30-year-old male who is 5'10" (178 cm), weighs 185 lbs (84 kg), has a 16-inch neck and 35-inch waist has approximately 19.5% body fat. This places him in the 'Average' category. His fat mass is about 36 lbs and lean mass is 149 lbs.
Tip: Measure in the morning before eating for consistency. Take each measurement twice and use the average. Keep the tape snug but not compressing skin.
Why Use a Body Fat Calculator?
Body fat percentage tells you what portion of your weight is fat versus muscle, bones, and organs - a much better health indicator than weight alone.
- Tracking fitness progress when the scale isn't moving (recomposition)
- Setting realistic body composition goals for athletic performance
- Understanding your body composition for health assessment
- Monitoring fat loss while preserving lean muscle mass
- Calculating lean mass for protein requirements and BMR formulas
- Comparing your body composition to fitness and athletic standards
Understanding Your Results
Body fat categories differ by gender because women naturally carry more essential fat for reproductive functions.
| Result | Meaning | Action |
|---|---|---|
| Men: 2-5% / Women: 10-13% | Essential Fat | Minimum fat needed for survival. Only competitive bodybuilders achieve this temporarily. |
| Men: 6-13% / Women: 14-20% | Athletes | Athletic level leanness. Visible abs and muscle definition. Requires dedicated training and nutrition. |
| Men: 14-17% / Women: 21-24% | Fitness | Lean, fit appearance. Sustainable for most active people. Some muscle definition visible. |
| Men: 18-24% / Women: 25-31% | Average | Acceptable for general health. Consider fat loss if closer to upper range. |
| Men: 25%+ / Women: 32%+ | Obese | Increased health risks. Focus on gradual fat loss through diet and exercise. |
Meaning: Essential Fat
Action: Minimum fat needed for survival. Only competitive bodybuilders achieve this temporarily.
Meaning: Athletes
Action: Athletic level leanness. Visible abs and muscle definition. Requires dedicated training and nutrition.
Meaning: Fitness
Action: Lean, fit appearance. Sustainable for most active people. Some muscle definition visible.
Meaning: Average
Action: Acceptable for general health. Consider fat loss if closer to upper range.
Meaning: Obese
Action: Increased health risks. Focus on gradual fat loss through diet and exercise.
Note: Ideal body fat increases slightly with age. What's healthy at 25 differs from what's healthy at 55. The calculator shows age-adjusted targets.
About Body Fat Calculator
Formula
Men: %BF = 495/(1.0324 - 0.19077×log10(waist-neck) + 0.15456×log10(height)) - 450 For women, hip measurement is included: %BF = 495/(1.29579 - 0.35004×log10(waist+hip-neck) + 0.22100×log10(height)) - 450. Measurements in centimeters.
Current Standards: American Council on Exercise categories: Essential (2-5% M / 10-13% F), Athletes (6-13% M / 14-20% F), Fitness (14-17% M / 21-24% F), Average (18-24% M / 25-31% F), Obese (25%+ M / 32%+ F).
Frequently Asked Questions
How do I measure correctly for the Navy method?
Neck: Measure below the larynx (Adam's apple) at the narrowest point, keeping tape perpendicular to the neck's axis. Waist: Measure at navel level for men, at the natural waist (narrowest point) for women, keeping tape horizontal. Hips (women only): Measure at the widest point of the buttocks. Stand relaxed, don't suck in your stomach. Measure directly on skin or over thin clothing.
Why is my body fat percentage different from my scale's reading?
Bioelectrical impedance scales can vary by 5-10% based on hydration, recent meals, exercise, and time of day. The Navy method is more consistent day-to-day. DEXA scans are the gold standard with 1-2% accuracy. Different methods also use different equations - some are calibrated for athletes, others for general population. Use the same method consistently to track trends rather than comparing across methods.
Can I have 'normal' weight but high body fat?
Yes, this is called 'skinny fat' or normal weight obesity. Someone with low muscle mass and high fat mass can have a healthy BMI but unhealthy body fat percentage. This is common in sedentary people who don't exercise. It's why body composition matters more than weight alone - you can be metabolically unhealthy at a 'normal' weight if too much of that weight is fat.
How fast can I safely reduce body fat?
Aim to lose 0.5-1% body fat per month, which typically means losing 1-2 pounds per week. Faster fat loss often results in muscle loss, which lowers metabolism and makes regain likely. To preserve muscle: maintain a moderate calorie deficit (500-750 below TDEE), eat adequate protein (0.7-1g per pound of body weight), and include strength training 2-3 times per week.
What body fat percentage shows visible abs?
For most men, abs become visible around 10-14% body fat. For women, 16-20%. Below these levels, muscle definition increases throughout the body. However, genetics affect fat distribution - some people show abs at higher percentages while others need to get very lean. Additionally, ab visibility requires actually having developed abdominal muscles through training, not just low body fat.