What is the US Navy body fat formula?

The US Navy body fat formula estimates body fat percentage using simple tape measurements. For men, it uses height, waist, and neck circumference. For women, it adds hip circumference. The formula was developed by Hodgdon and Beckett at the Naval Health Research Center and is used by the US military for fitness assessments. It has been validated against hydrostatic weighing with an accuracy of about 3-4%.

How do I measure my waist correctly?

Measure your waist at the level of your navel (belly button) while standing relaxed. Do not suck in your stomach. Use a flexible tape measure and keep it snug against your skin without compressing it. For the most accurate reading, measure at the end of a normal exhale. Take 2-3 measurements and use the average.

What is a healthy body fat percentage?

Healthy body fat ranges differ by gender. For men: athletes 6-13%, fitness 14-17%, average/acceptable 18-24%, obese 25%+. For women: athletes 14-20%, fitness 21-24%, average/acceptable 25-31%, obese 32%+. Essential fat (needed for survival) is 2-5% for men and 10-13% for women. Going below essential fat levels is dangerous.

Is body fat percentage better than BMI?

Body fat percentage is generally a better indicator of health than BMI because it directly measures fat versus lean mass. BMI cannot distinguish between muscle and fat, so muscular individuals often have a 'overweight' BMI despite being healthy. Body fat percentage gives a more accurate picture of body composition and health risk.

What is the difference between fat mass and lean mass?

Fat mass is the total weight of fat in your body. Lean mass (also called lean body mass or fat-free mass) is everything else: muscles, bones, organs, water, and connective tissue. For example, a 180 lb person with 20% body fat has 36 lbs of fat mass and 144 lbs of lean mass. Higher lean mass relative to fat mass is generally associated with better health and fitness.

How accurate is the US Navy method?

The US Navy method is accurate to within 3-4% of body fat compared to hydrostatic (underwater) weighing. It is most accurate for people in the average body fat range and may be less accurate for very lean or very overweight individuals. For the best accuracy, take measurements at the same time of day, use consistent measuring techniques, and average multiple readings.

CalcHive

Body Fat Calculator

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Calculate your body fat percentage using the US Navy method. Enter neck, waist, and hip measurements to get body fat %, fat mass, lean mass, and body fat category. Supports metric and imperial units.

Gender

Weight (lbs)

Height

Neck Circumference (in)

Waist Circumference (in)

Measure your neck at its narrowest point, your waist at the navel (belly button), and your hips at the widest point.

How to Use Body Fat Calculator

Select Metric (cm/kg) or Imperial (in/lbs) units.
Choose your gender.
Enter your weight and height.
Measure and enter your neck circumference at its narrowest point.
Measure and enter your waist circumference at your navel.
For women: also enter your hip circumference at the widest point.
View your body fat %, fat mass, lean mass, and category.
Check the reference table to see where you fall among body fat categories.

The US Navy Body Fat Formula

This calculator uses the US Navy body fat estimation method, developed by Hodgdon and Beckett at the Naval Health Research Center. It estimates body fat percentage from simple circumference measurements, making it accessible without specialized equipment.

Formula for Men:
Body Fat % = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450

Formula for Women:
Body Fat % = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450

All measurements must be in centimeters for the formula. The calculator automatically converts inches to centimeters when using Imperial units. Fat mass and lean mass are then calculated from the body fat percentage and your total body weight.

Frequently Asked Questions

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