HEALTH CALCULATOR
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy circumference method. Enter your sex, age, height, weight, and body measurements to see your estimated body fat percentage, fat mass, lean mass, and related body composition information.
Calculate Your Body Fat
Estimate body fat percentage using the U.S. Navy circumference method.
This falls within a commonly cited fitness reference range.
Fat Mass
Estimated portion of your current body weight represented by fat.
Lean Mass
Body weight remaining after subtracting estimated fat mass.
Age
Displayed for context; age is not part of the Navy circumference equation.
Estimated Body Fat
The percentage is an estimate from the selected circumference method, not a direct measurement of body composition.
Body Fat Range
Fat Mass vs. Lean Mass
Measurement Snapshot
The Navy method uses circumference relationships rather than body weight alone. Accurate tape placement can therefore materially affect the estimate.
Body Fat Categories
These ranges are general reference categories commonly used for educational comparison. They are not individualized medical targets.
What Is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that comes from fat tissue. Unlike body weight alone, body fat percentage can provide additional context about body composition by separating estimated fat mass from lean mass.
Body fat is a normal and necessary part of the human body. Some body fat is required for functions such as hormone production, temperature regulation, protection of organs, and energy storage.
This calculator provides an estimate rather than a direct measurement. Results can vary depending on how measurements are taken and on individual differences in body composition.
How Does the Body Fat Calculator Work?
This calculator uses the U.S. Navy body fat estimation method. The method estimates body fat percentage from body circumference measurements together with height and sex.
For men, the method uses measurements of the neck and waist together with height. For women, the calculation also incorporates the hip measurement.
The calculator first converts the measurements into the units required by the equations and then estimates body density and body fat percentage.
U.S. Navy Body Fat Formula
The U.S. Navy method uses logarithmic equations based on circumference measurements. The formulas differ between men and women.
For men, the calculation uses waist circumference minus neck circumference together with height.
For women, the calculation uses waist circumference, hip circumference, neck circumference, and height.
These equations are commonly presented using measurements in inches. The calculator handles the necessary unit conversion when you use metric measurements.
Body Fat Percentage vs. BMI
Body fat percentage and BMI measure different aspects of body composition. BMI compares weight with height, while body fat percentage attempts to estimate how much of that weight is fat.
Because BMI does not directly distinguish fat from muscle, two people with the same BMI can have different body compositions. Our BMI Calculator can be used alongside this calculator when you want to compare both measures.
| Measure | What it estimates | Primary inputs |
|---|---|---|
| Body fat percentage | Estimated proportion of body weight that is fat | Body measurements and height |
| BMI | Weight relative to height | Height and weight |
| Body weight | Total mass of the body | Weight measurement |
Body Fat Percentage Categories
Body fat ranges are often discussed differently for men and women because healthy body composition naturally differs between the sexes. Age can also influence how body fat should be interpreted.
The ranges below are provided as general reference information rather than as a medical diagnosis.
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average range | 18–24% | 25–31% |
| Higher range | 25%+ | 32%+ |
These categories should not be treated as strict boundaries for every individual. Fitness level, age, genetics, muscle mass, and measurement technique can all affect how a body fat estimate should be interpreted.
How to Measure Your Body Correctly
Measurement technique can have a meaningful effect on the result. Use a flexible measuring tape and keep the tape level and snug without compressing the skin.
Take measurements consistently and, when possible, use the same conditions each time. Measuring at different locations or pulling the tape tighter can produce different results even when your actual body composition has not changed.
Neck Measurement
Measure around the neck without compressing the tape. Keep the tape reasonably level and use the same technique each time you repeat the measurement.
Waist Measurement
Measure the waist consistently at the recommended location for the method. Avoid pulling the tape tightly against the body.
Hip Measurement
For women, the Navy method also uses hip circumference. Measure around the widest part of the hips while keeping the tape level.
Body Fat Calculator Example
Consider a man who is 30 years old, 175 cm tall, weighs 75 kg, has a neck circumference of 38 cm, and has a waist circumference of 85 cm.
The calculator converts the measurements into the units required by the U.S. Navy equation and uses the circumference difference together with height to estimate body fat percentage.
The resulting percentage is an estimate of body composition, not a direct measurement of the amount of fat stored in the body.
From Body Fat Percentage to Fat Mass
Once an estimated body fat percentage is available, it can also be used to estimate fat mass and lean body mass.
For example, if someone weighs 75 kg and has an estimated body fat percentage of 20%, their estimated fat mass would be approximately 15 kg and their estimated lean mass approximately 60 kg.
Lean mass is not the same thing as muscle mass. It also includes water, bones, organs, connective tissue, and other non-fat components of the body.
How Body Fat Relates to Weight Goals
Body fat percentage can provide useful context when setting weight-related goals. Two people can lose the same amount of weight while experiencing different changes in fat mass and lean mass.
If your goal is weight management, you can also use our Calorie Calculator to estimate daily calorie requirements based on your activity level.
Our BMR Calculator estimates the calories your body uses at rest, while the TDEE Calculator estimates total daily energy expenditure after activity is considered.
What Can Affect Body Fat Percentage?
Body composition can change over time due to changes in body weight, muscle mass, activity, diet, age, and other individual factors. Hydration and measurement technique can also affect some body composition measurements.
Because the U.S. Navy method is based on body circumferences, changes in where or how measurements are taken can influence the calculated result.
How Accurate Is a Body Fat Calculator?
A body fat calculator provides an estimate rather than a direct measurement. The U.S. Navy method is convenient because it requires only a measuring tape and basic body information, but it cannot capture every difference in individual body composition.
More specialized methods such as DEXA scans, hydrostatic weighing, air displacement testing, and certain bioelectrical impedance devices can provide additional information, although each method has its own limitations.
For tracking progress, consistency can be more useful than focusing on a single result. Using the same measurement method under similar conditions can make changes over time easier to interpret.
Frequently Asked Questions
What method does this body fat calculator use?
This calculator uses the U.S. Navy circumference method to estimate body fat percentage from body measurements and height.
Do men and women use the same formula?
No. The U.S. Navy method uses different equations for men and women. The women's equation also incorporates hip circumference.
Can I use metric measurements?
Yes. You can enter measurements using metric units. The calculator converts them for the underlying equations.
Is body fat percentage better than BMI?
They measure different things. BMI relates body weight to height, while body fat percentage estimates the proportion of body weight that is fat.
Is this calculator a medical assessment?
No. The result is an estimate based on a mathematical equation and should not be considered a medical diagnosis.