📏 Body Fat Calculator

Estimate your body fat percentage using the US Navy Method (circumference measurements) or the BMI Method. Get your fat mass, lean mass, and fitness category instantly.

Gender

Male Female

Height (cm)

Neck circumference (cm)

Waist circumference (cm)

Hip circumference (cm) (female only)

Measure at the narrowest point for waist, widest for hips. Measure neck just below the larynx.

What is Body Fat Percentage?

Body fat percentage is the proportion of your total body weight that consists of fat mass, expressed as a percentage. It is widely regarded as a more meaningful indicator of health and fitness than BMI because it distinguishes between fat and muscle — two people at the same BMI can have very different body compositions. An athlete may have 10% body fat and a BMI of 28 (classified "overweight"), while a sedentary individual at the same BMI may carry 28% body fat and face significant metabolic health risks.

Body fat percentage can be measured through several methods ranging from simple tape measure equations to laboratory-grade imaging. DEXA (dual-energy X-ray absorptiometry) is considered the gold standard. Hydrostatic (underwater) weighing and BodPod air displacement are highly accurate but require specialist equipment. Skinfold callipers and bioelectrical impedance scales are convenient but less accurate. The US Navy circumference method (used in this calculator) uses neck and waist (and hip for women) measurements to estimate body fat with reasonable accuracy for most adults.

Healthy body fat ranges differ by sex and age. The American Council on Exercise (ACE) classifies adult male essential fat at 2–5%, athletic at 6–13%, fit at 14–17%, acceptable at 18–24%, and obese at 25%+. For adult women the ranges are: essential 10–13%, athletic 14–20%, fit 21–24%, acceptable 25–31%, obese 32%+. These ranges shift slightly with age as fat distribution changes naturally.

Formulas Used

US Navy Method

Male: 495 / (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450

Female: 495 / (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450

BMI Method (Deurenberg)

Male: (1.20 × BMI) + (0.23 × age) − 16.2

Female: (1.20 × BMI) + (0.23 × age) − 5.4

How to Use This Calculator

1

Select Gender

Body fat standards differ significantly between males and females.
2

Choose a Method

The Navy method uses circumference measurements; BMI method uses height, weight, and age.
3

Enter Measurements

Use a flexible tape measure at the correct body landmarks for the most accurate result.
4

Review Your Category

See your body fat % alongside its fitness classification — Essential, Athletic, Fitness, Average, or Obese.

How the Body Fat Calculator Works

Formula, assumptions, and calculation steps for this health tool.

Methodology

Health calculators use published screening formulas and common planning rules to estimate body, nutrition, pregnancy, or fitness metrics from user inputs.

Calculation Steps

Enter the personal measurements requested by the tool.
Convert height, weight, age, dates, or activity inputs to standard units.
Apply the health or fitness formula for the selected metric.
Show the estimate with practical ranges or interpretation where available.

Assumptions and Limits

Results are educational estimates, not diagnosis or medical advice.
Individual factors such as medication, pregnancy, and medical history can change interpretation.
Consult a clinician for personal health decisions.

Reference basis: Common public-health and sports-science screening formulas.

Frequently Asked Questions

What is a healthy body fat percentage?

For men, 6–17% is considered fit to athletic. For women, 14–24% is in the fitness-to-average range. Essential fat — the minimum for survival — is about 2–5% for men and 10–13% for women. Very low body fat can be as dangerous as very high body fat.

How accurate is the Navy method?

The US Navy circumference method has a margin of error of ±3–4 percentage points vs. DEXA scan (gold standard). It is more accurate than the BMI method for most individuals but less accurate than hydrostatic weighing or DEXA. Accuracy depends heavily on consistent, correct measurement technique.

How can I reduce body fat?

A caloric deficit through diet and regular exercise is the most effective approach. Combining cardio (for overall fat loss) with resistance training (to preserve or build lean muscle) gives the best body composition results. Aim for 0.5–1 kg of fat loss per week for sustainable progress.

What is the difference between body fat % and BMI?

BMI (Body Mass Index) uses only height and weight — it cannot distinguish fat from muscle. Body fat percentage directly measures the proportion of fat in your body. A muscular athlete can have a high BMI but very low body fat, while a sedentary person may have a normal BMI with high body fat (skinny fat).

Real-World Applications

🏋️

Fitness Goal Setting

Athletes use body fat percentage targets to guide cutting (fat loss) and bulking phases, ensuring weight loss preserves muscle and weight gain minimises excess fat.

🏥

Clinical Obesity Assessment

Clinicians use body fat percentage alongside BMI to diagnose "normal weight obesity" — people with healthy BMI but dangerously high fat mass and low muscle — who face elevated metabolic risk.

💊

Pharmacokinetics

Fat-soluble drugs (certain anaesthetics, vitamins A/D/E/K) accumulate in adipose tissue. Knowing body fat percentage helps clinicians predict drug distribution volume and dosing intervals.

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Military & Law Enforcement

Armed forces worldwide use body fat percentage limits for service eligibility and fitness standards. The US Army uses the circumference-based tape test method for field assessments.

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Sports Performance Analysis

Swimming, gymnastics, cycling, and combat sports coaches track body fat percentage alongside power output to monitor athlete condition and optimise weight-class eligibility.

👩‍⚕️

Health Risk Stratification

Public health researchers use population body fat data to study links between adiposity and cardiovascular disease, type 2 diabetes, and all-cause mortality — more precisely than BMI alone.

Common Mistakes

Taking Measurements Incorrectly

Circumference measurements must be taken at specific anatomical landmarks: waist at the narrowest point (or navel for some formulas), hip at the widest point, neck just below the larynx. Inconsistent landmarks give unreliable results.

Comparing Different Methods

DEXA may read 18% where a bioimpedance scale reads 22% and the Navy tape method gives 20% for the same person. Stick to one measurement method for tracking progress — don't compare across methods.

Measuring After Exercise or a Meal

Bioelectrical impedance is especially sensitive to hydration. Measure in the morning before eating or exercising for the most consistent results.

Targeting Unhealthily Low Body Fat

Below essential fat levels (2% for men, 10% for women), hormonal disruption, organ damage, and immune suppression occur. "Lean" is not the same as "low as possible."

Using BMI as a Body Fat Proxy

BMI classifies weight relative to height but cannot distinguish fat from muscle. A muscular athlete can be "overweight" by BMI while having excellent body composition — always use a direct body fat estimate for body composition assessment.

ACE Body Fat Percentage Categories

Category	Men	Women
Essential Fat	2–5%	10–13%
Athletic	6–13%	14–20%
Fitness	14–17%	21–24%
Average	18–24%	25–31%
Obese	≥25%	≥32%

References

Hodgdon, J. A. & Beckett, M. B. Prediction of Percent Body Fat for US Navy Men and Women. Naval Health Research Center, 1984.
American Council on Exercise. Percent Body Fat Norms for Men and Women. acefitness.org.
Deurenberg, P. et al. Body Mass Index as a Measure of Body Fatness: Age- and Sex-Specific Prediction Formulas. British Journal of Nutrition, 1991.
Gallagher, D. et al. Healthy Percentage Body Fat Ranges. American Journal of Clinical Nutrition, 2000.
National Institute of Diabetes and Digestive and Kidney Diseases. Assessing Your Weight. niddk.nih.gov.