Body Fat Calculator
Estimate your body fat percentage using the US Navy tape measure method.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Body Fat Calculator
This calculator uses the US Navy circumference method, which requires only a tape measure and is one of the most accessible body fat estimation methods available. Here is how to take the measurements correctly:
- Waist: Measure at the narrowest point, typically around the navel level for males and at the narrowest visible point for females. Do not suck in.
- Neck: Measure just below the larynx (Adam's apple), sloping slightly downward at the front. Keep the tape snug but not compressing.
- Hip (females only): Measure at the widest point around the hips and buttocks.
- Height: Use your actual height without shoes.
- Weight (optional): Enter your weight to see lean mass and fat mass in pounds or kilograms.
Take each measurement twice and average the results for better accuracy. Use the Share button to save a link with your inputs.
About the US Navy Body Fat Formula
The US Navy method calculates body fat using circumference measurements and height. For males: 495 / (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450. For females: 495 / (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.22100 × log10(height)) - 450. All measurements must be in centimeters for this formula.
The method has a margin of error of approximately 3-4 percentage points compared to DEXA scan (the gold standard). While not as precise as hydrostatic weighing or DEXA, it is accurate enough to track changes over time and far more accessible. The formula is used by the US military to assess fitness standards.
Frequently Asked Questions
What is a healthy body fat percentage?
Healthy ranges differ by sex. For males: essential fat is 2-5%, athletic is 6-13%, fitness is 14-17%, average is 18-24%, and obese is 25% or higher. For females: essential fat is 10-13%, athletic is 14-20%, fitness is 21-24%, average is 25-31%, and obese is 32% or higher. Women naturally carry more essential fat due to hormonal and reproductive functions.
How accurate is the Navy body fat method?
The US Navy method is accurate to within 3-4 percentage points of DEXA scan for most people. It tends to be less accurate for very lean or very obese individuals. Measurement technique matters: inconsistent tape placement can change the result by 1-2%. Taking each measurement twice and averaging improves accuracy. For tracking progress over time, it is highly reliable as long as you measure consistently.
Where do I measure waist circumference?
For the Navy body fat formula, males measure the waist at the level of the navel. Females measure at the narrowest point of the abdomen, which is typically slightly above the navel. This differs from the waist measurement used in BMI-related guidelines, which is usually at the midpoint between the lowest rib and the hip bone. Using the correct landmark for each formula is important for accuracy.
What is the difference between body fat percentage and BMI?
BMI uses only height and weight and cannot distinguish fat from muscle. Body fat percentage directly measures the proportion of your body that is fat versus lean tissue. Two people with the same BMI can have very different body fat percentages: an athlete with a lot of muscle mass can have a high BMI but low body fat, while a sedentary person with less muscle can have a normal BMI but a high body fat percentage (sometimes called "skinny fat").