Body Fat Calculator - Calculate Your Body Fat Percentage (US Navy Method)

Free body fat calculator using the US Navy method. Calculate your body fat percentage, fat mass, lean mass, and fitness category with accurate circumference measurements.

9 min read

Body Fat Calculator

Free body fat calculator using the US Navy method. Calculate your body fat percentage, fat mass, lean mass, and fitness category with accurate circumference measurements.

iAbout This Calculator

Understanding your body fat percentage is essential for assessing your overall health and fitness level. Unlike BMI, which only considers height and weight, body fat percentage tells you the actual proportion of fat tissue in your body. Our free body fat calculator uses the US Navy method, a scientifically validated formula that requires simple circumference measurements you can take at home with a measuring tape. Whether you're tracking fitness progress, planning a weight loss journey, or simply curious about your body composition, this calculator provides accurate estimates along with your fitness category and fat/lean mass breakdown.

?How to Use

1
Select your gender, as the calculation formula differs between males and females.
2
Enter your age in years. While age doesn't directly affect the US Navy formula, it's useful for contextual health information.
3
Input your weight in kilograms. This is needed to calculate fat mass and lean mass.
4
Enter your height in centimeters for the body fat percentage calculation.
5
Measure your neck circumference at the narrowest point (below the Adam's apple for men) and enter in centimeters.
6
Measure your waist circumference at the navel level (or at the narrowest point for women) and enter in centimeters.
7
For females only: Measure your hip circumference at the widest point and enter in centimeters.
8
Click Calculate to see your body fat percentage, category, fat mass, and lean mass.

fFormula

\text{Male: } BF\% = 495 / (1.0324 - 0.19077 \times \log_{10}(waist - neck) + 0.15456 \times \log_{10}(height)) - 450

The US Navy body fat formula uses logarithmic calculations based on circumference measurements. For males, it considers waist minus neck circumference and height. For females, it adds hip circumference to account for different fat distribution patterns.

BF%: Body fat percentage
waist: Waist circumference in cm
neck: Neck circumference in cm
hip: Hip circumference in cm (females only)
height: Height in cm

Examples

Fit Male

Inputs: gender: male, age: 30, weight: 75, height: 178, neck: 38, waist: 82

14.5% (Fitness)

A 30-year-old male with these measurements has approximately 14.5% body fat, placing him in the Fitness category. Fat mass: 10.9 kg, Lean mass: 64.1 kg.

Athletic Female

Inputs: gender: female, age: 28, weight: 60, height: 165, neck: 32, waist: 68, hip: 94

18.2% (Athletes)

A 28-year-old female with these measurements has approximately 18.2% body fat, placing her in the Athletes category. Fat mass: 10.9 kg, Lean mass: 49.1 kg.

Average Male

Inputs: gender: male, age: 45, weight: 85, height: 175, neck: 40, waist: 95

22.8% (Average)

A 45-year-old male with these measurements has approximately 22.8% body fat, placing him in the Average category. Fat mass: 19.4 kg, Lean mass: 65.6 kg.

Average Female

Inputs: gender: female, age: 35, weight: 68, height: 162, neck: 33, waist: 78, hip: 102

27.5% (Average)

A 35-year-old female with these measurements has approximately 27.5% body fat, placing her in the Average category. Fat mass: 18.7 kg, Lean mass: 49.3 kg.

Use Cases

Fitness Progress Tracking

Monitor changes in body composition over time as you exercise and adjust your diet. Body fat percentage is more meaningful than scale weight for tracking fitness gains.

Weight Loss Planning

Set realistic body fat goals and calculate how much fat mass you need to lose. Understanding your lean mass helps ensure you're losing fat, not muscle.

Athletic Performance

Athletes can optimize their body composition for their sport. Different sports have different ideal body fat ranges for peak performance.

Health Assessment

Body fat percentage is a better indicator of health risks than BMI alone. High body fat is associated with increased risk of heart disease, diabetes, and other conditions.

Nutrition Planning

Calculate your lean body mass to determine appropriate protein intake and caloric needs for maintaining or building muscle.

Frequently Asked Questions

How accurate is the US Navy body fat method?

The US Navy method is accurate within 3-4% of more sophisticated methods like DEXA scans for most people. It's considered one of the most reliable circumference-based methods and is officially used by the US military for fitness assessments.

What's a healthy body fat percentage?

Healthy ranges vary by gender. For men: Athletes 6-13%, Fitness 14-17%, Average 18-24%. For women: Athletes 14-20%, Fitness 21-24%, Average 25-31%. Essential fat (minimum needed for health) is 2-5% for men and 10-13% for women.

Why is the calculation different for males and females?

Women naturally carry more body fat than men due to biological differences including hormones and reproductive functions. Women store more fat in hips and thighs, which is why hip measurement is included in the female formula.

Is body fat percentage better than BMI?

Body fat percentage provides more useful information about body composition than BMI. BMI can classify muscular individuals as overweight and may miss unhealthy body composition in those with normal weight but high fat percentage (skinny fat).

How often should I measure body fat?

Measure every 2-4 weeks if you're actively trying to change your body composition. Body fat changes slowly, so daily measurements aren't meaningful and can be discouraging due to measurement variability.

Conclusion

Knowing your body fat percentage provides valuable insight into your overall health and fitness level beyond what the scale can tell you. The US Navy method offers a practical, no-cost way to estimate body fat using simple measurements you can take at home. While not as precise as laboratory methods, it's accurate enough for tracking progress and making informed decisions about your fitness and nutrition goals. Remember that healthy body fat ranges vary by gender and age, and the goal should be optimal health rather than achieving the lowest possible percentage.