Body Fat Percentage Calculator

Using the U.S. Navy circumference method to estimate body composition.

Your Results

What is Body Fat Percentage?

Body Fat Percentage (BFP) is the total mass of fat in your body divided by your total body mass; it includes both essential body fat and storage body fat. Unlike the Body Mass Index (BMI), which only considers height and weight, BFP provides a more accurate measure of your fitness level and body composition by distinguishing between fat mass and lean mass. Essential fat is necessary for maintaining life and reproductive functions, while storage fat provides energy and protects your internal organs. This calculator uses the U.S. Navy method, a circumference-based formula, to provide a convenient and reliable estimate of your body composition.

Body Fat Percentage Formula and Explanation

The U.S. Navy Body Fat formula provides a simple yet effective way to estimate body fat using circumference measurements. The formulas differ for males and females due to differences in body fat distribution.

Male Formula:

BFP % = 86.010 * log10(Waist - Neck) - 70.041 * log10(Height) + 36.76

Female Formula:

BFP % = 163.205 * log10(Waist + Hip - Neck) - 97.684 * log10(Height) - 78.387

These formulas use the base-10 logarithm of the circumference and height measurements to estimate the body fat percentage. All measurements should be in inches for these specific formulas.

Description of variables used in the formula.

Variable	Meaning	Unit (for formula)	Typical Range
Height	Your total height without shoes.	Inches	55 – 80 in
Neck	Circumference of your neck below the larynx.	Inches	12 – 20 in
Waist	Circumference of your waist at the navel (men) or narrowest point (women).	Inches	25 – 50 in
Hip	(Females only) Circumference of your hips at the widest point.	Inches	30 – 55 in

Practical Examples

Example 1: Male

• Inputs: Height: 71 in, Weight: 180 lbs, Neck: 16 in, Waist: 35 in
• Units: Imperial
• Calculation: BFP = 86.010 * log10(35 – 16) – 70.041 * log10(71) + 36.76 ≈ 17.8%
• Result: This individual has an estimated body fat percentage of 17.8%, which falls within the “Fitness” category for men.

Example 2: Female

• Inputs: Height: 65 in, Weight: 145 lbs, Neck: 13 in, Waist: 29 in, Hip: 40 in
• Units: Imperial
• Calculation: BFP = 163.205 * log10(29 + 40 – 13) – 97.684 * log10(65) – 78.387 ≈ 24.5%
• Result: This individual has an estimated body fat percentage of 24.5%, which is in the “Fitness” to “Average” range for women.

How to Use This Body Fat Percentage Calculator

1. Select Your Gender: Choose ‘Male’ or ‘Female’ as the formula is different for each.
2. Choose Your Units: Select ‘Imperial’ (inches, lbs) or ‘Metric’ (cm, kg). The calculator will convert as needed.
3. Enter Your Measurements: Accurately measure your height, weight, neck, and waist. If you selected ‘Female’, also enter your hip measurement.
4. Calculate: Click the “Calculate” button to see your results.
5. Interpret Results: The calculator will display your Body Fat Percentage, Body Fat Mass, and Lean Body Mass. A chart will also visualize your body composition.

Key Factors That Affect Body Fat Percentage

• Genetics: Your genes play a significant role in determining how and where your body stores fat.
• Age: Body fat percentage naturally tends to increase with age, while muscle mass decreases.
• Diet: Consuming more calories than you burn leads to fat storage. The quality of your food also matters; processed foods and sugary drinks can contribute more to fat gain.
• Physical Activity: Regular exercise, especially a combination of cardiovascular and strength training, helps burn fat and build lean muscle mass.
• Hormones: Hormones like cortisol, insulin, and thyroid hormones can significantly impact your metabolism and fat storage.
• Sleep: Lack of adequate sleep can disrupt hormones that regulate appetite and metabolism, leading to increased fat storage.

To learn about healthy weight ranges, you can use a BMI Calculator.

Frequently Asked Questions (FAQ)

1. How accurate is the U.S. Navy method?

The U.S. Navy method is considered to be a good estimation tool for body fat, generally accurate within 1-3% for most people. However, it’s not as precise as clinical methods like hydrostatic weighing or DXA scans.

2. Is body fat percentage better than BMI?

BFP is often considered a better indicator of health than BMI because it distinguishes between fat and muscle. A muscular person might have a high BMI and be classified as overweight, while their body fat percentage is actually very low and healthy.

3. What is a healthy body fat percentage?

For men, a healthy range is typically 18-24%, while for women it’s 25-31%. Athletes often have lower percentages (6-13% for men, 14-20% for women).

4. How do I measure my circumferences correctly?

Use a flexible measuring tape. For the neck, measure below the Adam’s apple. For the waist, measure at the navel for men and the narrowest part for women. For hips, measure at the widest point. Ensure the tape is snug but not compressing the skin.

5. Why is there no weight input in the formula?

The U.S. Navy formula is a circumference-based method and does not use weight in its primary BFP calculation. However, this calculator uses your weight to determine your Body Fat Mass and Lean Body Mass after the percentage is found.

6. Can I use this calculator if I’m under 18?

These formulas were developed for adults and may not be accurate for children or adolescents who are still growing.

7. How often should I measure my body fat?

Tracking your body fat percentage monthly can be a good way to monitor progress. Daily fluctuations can occur, so looking at the longer-term trend is more useful.

8. What is the difference between essential and storage fat?

Essential fat is vital for normal body functions and is found in organs, bone marrow, and nerves. Storage fat is the energy reserve stored in adipose tissue. Women naturally have a higher percentage of essential fat than men.