Use this free body fat calculator to estimate your body fat percentage based on simple body measurements. Enter your height, weight, waist circumference, and a few other details. The calculator returns an estimate of your total body fat, lean body mass, and where you fall in standard body fat percentage ranges.

No calipers or special equipment needed. A tape measure and a scale are enough.

How the Body Fat Calculator Works

This body fat calculator uses the U.S. Navy circumference method. It estimates body fat percentage based on the relationship between specific body measurements and overall body composition.

For men, the calculator uses neck circumference, waist circumference, and height. For women, it adds a hip measurement. These inputs feed into a formula developed by the U.S. Navy to estimate body density, which is then converted to a body fat percentage.

The calculator provides an estimate, not a clinical measurement. It works well for most adults who want a quick baseline without visiting a lab or buying specialized equipment.

What is body fat percentage? It is the portion of your total body weight made up of fat. If you weigh 180 pounds and have 20% body fat, roughly 36 pounds of your weight is fat tissue. The rest is lean body mass: muscle, bone, water, and organs.

What is the difference between body fat percentage and BMI? BMI (body mass index) uses only height and weight. It cannot tell how much fat is stored versus how much is muscle. Two people with the same BMI can have very different fat levels. Body fat percentage is a more direct estimate of actual body composition.

Waist Circumference and Other Circumference Measurements

Accurate circumference measurements are the most important step. Small errors here shift the final estimate by several percentage points.

How to measure waist circumference: Stand relaxed. Wrap the tape measure around your bare waist at the navel. Keep the tape level and snug, but do not compress the skin. Measure after a normal exhale.

Neck circumference: Measure just below the larynx (Adam's apple). Keep the tape level. Look straight ahead.

Hip circumference (women only): Measure at the widest point of the hips and buttocks. Keep the tape level all the way around.

Tips for consistent readings:

Use a flexible cloth or vinyl tape measure.
Measure in the morning before eating or exercising.
Take each measurement twice. If the two readings differ, measure a third time and use the middle value.
Record values in inches or centimeters, matching the units the calculator expects.

Calculate Body Fat From Body Weight and Total Body Weight

Body weight alone tells you very little about how much fat you carry. Two people at the same total body weight can have very different amounts of fat and muscle.

The calculator combines your body weight with your circumference measurements to estimate the split between fat mass and lean body mass. This gives a clearer picture than stepping on a scale.

Does muscle mass affect body fat percentage? Yes. Muscle is denser than fat. A person with more muscle mass at the same weight will show a lower body fat percentage. This is exactly why body fat percentage is more useful than weight or BMI alone for assessing body composition.

But how does knowing your total body weight help with knowing how much fat you have? On its own, it does not. That is why the calculator pairs weight with circumference measurements. The ratio between your waist (where fat accumulates most) and other dimensions estimates how much of your body weight is fat versus lean tissue.

Fat Mass and Body Composition

Your results include two key numbers:

Fat mass: The estimated weight of fat stored in your body. This includes both essential fat and excess body fat.
Lean body mass: Everything that is not fat. Muscle, bone, water, connective tissue, and organs.

What is essential body fat? Essential fat is the minimum amount of fat needed for normal body functions. It protects organs, regulates hormones, and supports the nervous system. For men, essential fat is roughly 2% to 5% of body weight. For women, it is roughly 10% to 13%. Dropping below these levels is dangerous.

Actual body composition is more nuanced than a single percentage. Fat is stored in different places. Some is subcutaneous fat (under the skin), and some is visceral fat (around internal organs). The calculator estimates total body fat but cannot distinguish between these types.

Body Fat Percentage Range for a Healthy Body

A healthy body fat percentage depends on your age, sex, and activity level. There is no single ideal number. Instead, health organizations publish ranges.

General guidelines for adults:

Category	Men	Women
Essential fat	2%–5%	10%–13%
Athletes	6%–13%	14%–20%
Fitness	14%–17%	21%–24%
Average	18%–24%	25%–31%
Above average	25%+	32%+

These are estimates based on population data. Individual health depends on many factors beyond fat percentages alone.

Can you be a healthy weight but have high body fat? Yes. This is sometimes called "normal weight obesity." A person can have a BMI in the normal range but carry excess body fat and low muscle mass. Body fat percentage catches this pattern where BMI does not.

Healthy Body Fat Percentage by Age and Sex

Fat percentages tend to rise with age, even in healthy adults. A 50 year old with 22% body fat is not in the same situation as a 25 year old at 22%.

Women carry more essential fat than men due to reproductive physiology. Healthy body fat ranges for women are consistently about 8 to 12 percentage points higher than the equivalent range for men.

General trends:

Ages 20 to 39: Men typically range 8% to 20%. Women typically range 21% to 33%.
Ages 40 to 59: Men typically range 11% to 22%. Women typically range 23% to 34%.
Ages 60+: Both sexes tend to carry slightly more fat at equivalent health levels.

These ranges vary by source. Use them as a reference point, not a hard rule.

Fat Percentages and Fat Around the Midsection

Where fat is stored matters as much as how much fat you carry. Fat stored around the midsection, particularly visceral fat around internal organs, correlates more strongly with metabolic and cardiovascular risk than fat stored in the hips or thighs.

A large waist circumference is an independent risk factor even when total body fat percentage is within a normal range. General thresholds often cited:

Men: waist circumference above 40 inches (102 cm) increases risk.
Women: waist circumference above 35 inches (88 cm) increases risk.

The shape of your body can help tell you how much abdominal fat you have. An "apple" body shape (fat accumulates around the waist) is associated with higher health risk than a "pear" shape (fat stored in hips and thighs).

This calculator does not measure visceral fat directly. However, a high waist circumference input is one signal worth discussing with a healthcare provider.

Measure Body Fat at Home

You do not need a lab to estimate body fat. Several home methods give useful results for tracking trends over time.

Way to Measure Body Fat With a Tape Measure

The tape measure method is what this calculator uses. It is free, repeatable, and requires no special skill.

Steps:

Gather a flexible tape measure and a scale.
Weigh yourself in the morning, before eating.
Take your circumference measurements following the guidelines above.
Enter all values into the calculator.

For tracking body fat over time, consistency matters more than absolute accuracy. Measure at the same time of day, in the same conditions, every time. This reduces noise and lets you see real trends.

How often should I measure my body fat percentage? Every two to four weeks is practical. Body fat changes slowly. Measuring more often can create misleading fluctuations from water retention or measurement variability.

Other home methods:

Skinfold caliper: A handheld tool that pinches skin at specific sites to measure subcutaneous fat thickness. Affordable calipers are widely available. Accuracy depends on technique and consistent site selection.
Smart scales (bioelectrical impedance): These send a small electrical current through your body. They are convenient but sensitive to hydration, meal timing, and other variables. Results can swing by several percentage points within the same day.

The Most Accurate Way to Measure Body Fat Percentage

No home method is truly precise. The most accurate ways to measure body fat require clinical equipment:

DEXA scan (dual energy X-ray absorptiometry): Considered a gold standard. It separates fat, lean tissue, and bone mineral. Accurate to within 1% to 2%. Available at clinics and some gyms. Typical cost: $40 to $100 per scan.
Hydrostatic weighing (underwater weighing): Measures body density by comparing weight on land to weight submerged. Very accurate. Less widely available.
Bod Pod (air displacement plethysmography): Uses air displacement instead of water. Comparable accuracy to hydrostatic weighing.

For most people, a clinical scan is useful as an occasional benchmark. For ongoing tracking, a consistent home method (tape measure or caliper) is more practical.

Calculate Your Body Fat Percentage Without the Calculator

If you want to understand the math behind the estimate, here is a simplified version of the U.S. Navy body fat formula.

For men:

Body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76

For women:

Body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

All measurements are in inches. The log10 values are base 10 logarithms.

This is the same formula the calculator uses. Working it by hand confirms your understanding, but the calculator handles the math instantly and avoids rounding errors.

How is body fat percentage calculated? Most estimate methods, including this one, use body measurements to estimate body density. A conversion formula (typically the Siri equation) then translates density into a body fat percentage. Different methods (calipers, circumference, DEXA) estimate density through different physical principles, but the underlying logic is similar.

Measure Body Fat Percentage: Body Fat at Home vs. Clinical Methods

Every method has trade-offs between cost, convenience, and accuracy.

Method	Cost	Accuracy	Convenience
Tape measure (Navy method)	Free	±3%–4%	High
Skinfold caliper	$10–$30	±3%–4% (technique dependent)	Moderate
Bioelectrical impedance scale	$30–$100	±4%–5%	High
DEXA scan	$40–$100 per scan	±1%–2%	Low (appointment needed)
Hydrostatic weighing	$50–$150 per session	±1%–2%	Low
Bod Pod	$40–$75 per session	±1%–2%	Low

Are body fat calculators accurate? They provide a reasonable estimate for most people. The Navy method has been validated across large populations. Individual results can deviate by a few percentage points from clinical measurements, especially for people with very high or very low muscle mass. The value is in tracking direction over time, not treating any single number as exact.

What does a 20% body fat percentage look like? For men, 20% typically means a soft midsection with little visible muscle definition. For women, 20% is relatively lean, often with visible muscle tone. Visual appearance at the same percentage varies widely depending on where fat is stored and overall muscle mass.

Healthy Body Fat and How to Lose Fat

If your results suggest you are carrying excess body fat, losing fat is a matter of sustained energy balance. You need to use more calories than you consume over time.

Practical steps:

Modest calorie deficit. A 300 to 500 calorie daily deficit supports steady fat loss without extreme restriction.
Strength training. Resistance exercise preserves and builds lean body mass. This matters because you want to lose fat, not muscle.
Protein intake. Adequate protein (roughly 0.7 to 1 gram per pound of body weight) supports muscle retention during a deficit.
Consistent tracking. Measure body fat percentage every few weeks using the same method to confirm you're losing fat, not just weight.

How long does it take to lower body fat percentage? A realistic rate is 0.5% to 1% body fat per month for most people, though this depends on starting point, diet, and training. Patience matters. Rapid weight loss often means muscle loss, not just fat loss.

How does body fat percentage relate to visible abs? For most men, abdominal muscles become visible around 10% to 14% body fat. For most women, around 16% to 20%. Genetics and where your body stores fat influence this significantly.

Body recomposition (losing fat while gaining muscle) is possible, especially for beginners or those returning to training. It is slower than focused fat loss but produces favorable changes in actual body composition.

How do I use my body fat percentage result to set a goal? Compare your result to the healthy ranges above. Set a target within the healthy range for your age and sex. Focus on the trend over weeks and months rather than any single measurement.