Use this free Body Fat Calculator to estimate your body fat percentage using the US Navy circumference method. Enter your height, weight and tape measurements to see your estimated body fat, fat mass and lean body mass.
Calculate Your Body Fat Percentage
Use a few simple body measurements to estimate your body fat, fat mass and lean body mass.
What Is Body Fat Percentage?
Body fat percentage describes how much of your total body weight is estimated to come from fat.
For example, if someone weighs 80 kg and has an estimated body fat percentage of 20%, approximately 16 kg of their body weight would be fat mass.
The remaining weight includes lean tissues such as muscle, bone, organs and body water.
Body fat percentage can provide information that body weight alone cannot.
How Does the Body Fat Calculator Work?
Our calculator uses the US Navy circumference method.
This method estimates body fat using a flexible tape measure and a small number of body measurements.
For men, the calculation uses:
- height
- neck circumference
- waist circumference
For women, it uses:
- height
- neck circumference
- waist circumference
- hip circumference
The relationship between these measurements is used to estimate body density and body fat percentage.
Current body-fat calculators commonly use this method because it requires no specialist equipment and can be repeated at home.
How to Measure for the Body Fat Calculator
Measurement technique matters.
Use a flexible tape measure and try to measure under similar conditions each time.
Height
Stand upright without shoes and measure your full standing height.
Neck Circumference
Measure around the neck with the tape level and snug against the skin without squeezing.
Waist Circumference
Measure consistently at the same location each time.
For the male Navy calculation, the waist measurement is commonly taken around the abdomen near the navel.
For women, published implementations may use a defined waist location together with the hip measurement.
The most important thing for progress tracking is to use the same measurement technique each time.
Hip Circumference
For women, measure around the widest part of the hips and buttocks while keeping the tape level.
Taking two or three measurements and averaging them can reduce simple tape-measure errors.
US Navy Body Fat Formula
The US Navy method uses different equations for males and females because body-fat distribution patterns differ.
The male calculation uses the difference between waist and neck circumference relative to height.
The female calculation additionally uses hip circumference.
Our calculator converts imperial measurements to metric internally before applying the calculation.
What Is Fat Mass?
Fat mass is the estimated amount of your body weight that comes from fat.
The calculation is:
Fat Mass = Body Weight × Body Fat Percentage
For example:
Body weight: 80 kg
Body fat: 20%
Estimated fat mass:
80 × 0.20 = 16 kg
What Is Lean Body Mass?
Lean body mass is everything in your body other than fat mass.
It includes:
- muscle
- bone
- organs
- body water
- other non-fat tissue
The simplified calculation is:
Lean Body Mass = Body Weight − Fat Mass
Using the previous example:
Body weight: 80 kg
Fat mass: 16 kg
Estimated lean body mass:
64 kg
Lean body mass can also be useful in other fitness calculations.
Body Fat Percentage vs BMI
BMI and body fat percentage measure different things.
BMI uses only:
- body weight
- height
Body fat percentage attempts to estimate how much of your body weight comes from fat.
This difference matters because two people with the same BMI can have very different body compositions.
For example, someone with substantial muscle mass may have a relatively high BMI even if their body-fat percentage is not particularly high.
Is Body Fat Percentage Better Than Body Weight?
Neither measurement tells the complete story.
Body weight is simple and useful for tracking overall change.
Body fat percentage attempts to provide additional information about body composition.
A person could lose body fat while gaining muscle and see relatively little change on the scale.
In that situation, body composition measurements may provide useful additional context.
What Is a Healthy Body Fat Percentage?
There is no single perfect body-fat percentage for everyone.
Reference categories vary according to the organization and method used.
General fitness charts often separate ranges into categories such as:
- essential fat
- athletic
- fitness
- acceptable or average
- higher body-fat range
These ranges also differ between men and women.
The category shown by our calculator is intended only as a broad fitness reference and should not be treated as a medical diagnosis.
Body Fat Ranges for Men
Broad fitness-reference categories often look approximately like:
Essential fat: up to about 5%
Athletic: about 6–13%
Fitness: about 14–17%
Average / acceptable: about 18–24%
Higher values fall above these general fitness-reference ranges.
Body Fat Ranges for Women
Broad fitness-reference categories are generally higher for women because normal physiological fat levels differ.
Typical reference ranges often look approximately like:
Essential fat: up to about 13%
Athletic: about 14–20%
Fitness: about 21–24%
Average / acceptable: about 25–31%
Higher values fall above these general reference ranges.
These categories are descriptive references rather than treatment thresholds.
How Accurate Is the US Navy Body Fat Method?
No tape-measure method can provide a perfectly accurate body-fat measurement.
The US Navy method is a regression-based estimate.
Its result can differ from laboratory techniques by several percentage points for an individual. Current calculator references commonly describe an error in roughly the 3–4 percentage-point range, depending on the person and measurement quality.
That means a result of 18% should not be interpreted as proof that your exact body-fat level is precisely 18.0%.
The method is more useful for estimating and tracking trends.
Why Measurement Consistency Matters
A small difference in tape placement or tension can change the calculated result.
For better consistency:
- Measure at the same locations.
- Use the same tape.
- Keep the tape level.
- Do not flex your muscles.
- Avoid pulling the tape excessively tight.
- Measure under similar conditions.
- Consider averaging multiple measurements.
Consistency is usually more valuable than repeatedly switching between different measurement techniques.
Body Fat Scales vs Tape Measurements
Many smart scales estimate body composition using bioelectrical impedance.
These devices send a small electrical signal through the body and estimate body composition from resistance.
Results can change with factors such as hydration.
Tape measurements use a completely different method based on body circumferences.
Neither method should be considered equivalent to a laboratory measurement.
If you are tracking progress, using the same method consistently can be more useful than frequently switching methods.
What Are More Accurate Body Fat Tests?
More specialized body-composition methods include:
- DEXA scans
- hydrostatic weighing
- air-displacement methods
- professionally performed skinfold measurements
These methods may provide additional information, but they can also be more expensive or less accessible.
For everyday fitness tracking, circumference methods offer a convenient option requiring only a tape measure.
Can Body Fat Percentage Change Without Weight Changing?
Yes.
Suppose someone loses fat while gaining approximately the same amount of lean mass.
Their total body weight could remain similar even though their body composition changes.
This is one reason relying only on scale weight can sometimes miss changes occurring during resistance training.
How Often Should You Measure Body Fat?
There is usually little value in measuring body fat every day.
Tape measurements contain natural measurement error, and body composition changes slowly.
For progress tracking, measuring every few weeks under similar conditions is generally more useful.
Look at the trend rather than small changes between individual readings.
Body Fat Percentage and Muscle Gain
During a muscle-building phase, both body weight and body composition can change.
Monitoring body weight together with waist measurements and training performance can provide more context than looking at any single number.
If your goal is muscle gain, use our Macro Calculator to estimate daily calories and macronutrients.
Our Protein Calculator can also help estimate a practical daily protein target.
Body Fat Percentage and Fat Loss
During a fat-loss phase, your body-fat estimate may gradually decrease if you lose fat while maintaining lean tissue.
Use our Calorie Deficit Calculator to estimate a starting calorie deficit.
You can also use our TDEE Calculator to estimate maintenance calorie needs before creating a deficit.
What Should You Calculate Next?
Once you know your estimated body-fat percentage, several other calculations become more useful.
Use our Calorie Deficit Calculator to estimate calories for weight loss.
Use our TDEE Calculator to estimate total daily energy expenditure.
Use our Macro Calculator to calculate protein, carbohydrate and fat targets.
Use our Protein Calculator for a dedicated daily protein estimate.
Future body-composition tools will also include Lean Body Mass and FFMI calculators.
Frequently Asked Questions
How can I calculate body fat percentage at home?
You can estimate body-fat percentage using circumference measurements and a method such as the US Navy formula. Our calculator performs the calculation automatically.
What measurements do men need?
The male US Navy calculation uses height, neck circumference and waist circumference.
What measurements do women need?
The female calculation uses height, neck circumference, waist circumference and hip circumference.
Do I need my body weight to calculate body fat percentage?
The circumference equation itself estimates body-fat percentage from body measurements. Our calculator also asks for weight so it can calculate estimated fat mass and lean body mass.
Is the Navy body fat method accurate?
It is useful as an estimate but can differ from laboratory measurements by several percentage points. Consistent measurement technique improves its usefulness for tracking trends.
Is body fat percentage more useful than BMI?
They provide different information. BMI describes weight relative to height, while body-fat percentage attempts to estimate the proportion of body weight that is fat.
Can I measure body fat every day?
You can, but daily measurement is usually unnecessary and small measurement errors can create noise. Tracking every few weeks under similar conditions is generally more useful.
Why did my body fat percentage change suddenly?
Tape placement, hydration, abdominal bloating and measurement technique can all affect the result. Look at repeated measurements rather than one reading.
Can muscle affect body fat percentage?
Yes. Body composition reflects the relative amounts of fat and lean tissue. Changes in muscle mass can therefore affect body-fat percentage even when total body weight changes differently.
Is very low body fat always healthier?
No. Extremely low body-fat levels are not automatically healthier and may be inappropriate for some people. Health should not be judged by a single body-composition number.
Disclaimer
The Body Fat Calculator and information on this page are provided for general educational and fitness-planning purposes only.
The US Navy circumference method provides an estimate and does not directly measure body fat.
Results should not be used as a medical diagnosis or as a substitute for professional assessment.
People with medical conditions, pregnancy, concerns about body composition, or a history of eating disorders should seek guidance from an appropriately qualified healthcare professional.