Body Fat Calculator
This body fat calculator estimates your body fat percentage using the US Navy circumference method. Enter your neck, waist, and hip measurements along with height to get your body fat percentage, lean mass, and fitness category classification.
Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy Method. Enter your measurements below.
Provide weight to calculate fat mass and lean mass.
Frequently Asked Questions
How do you calculate body fat percentage?
Body fat percentage can be calculated using several methods. The US Navy circumference method uses measurements of your neck, waist, and hip circumferences along with height to estimate body fat through a logarithmic formula. Other methods include skinfold calipers, bioelectrical impedance analysis (BIA), DEXA scans, and hydrostatic weighing, each varying in accuracy and accessibility.
What is the US Navy body fat formula?
The US Navy body fat formula for men is: %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women: %BF = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. All measurements are in centimeters. This formula was developed by Hodgdon and Beckett at the Naval Health Research Center and is the standard method used by the US military.
What is a healthy body fat percentage?
Healthy body fat ranges vary by gender and age. For men, essential fat is 2-5%, athletes range from 6-13%, fitness level is 14-17%, acceptable is 18-24%, and above 25% is considered obese. For women, essential fat is 10-13%, athletes range from 14-20%, fitness level is 21-24%, acceptable is 25-31%, and above 32% is considered obese. These ranges provide general guidelines.
How accurate is the Navy body fat method?
The US Navy method has a typical error margin of 1-3% compared to more precise methods like DEXA scanning. It tends to be most accurate for people with average body compositions and may be less accurate for very muscular individuals or those with unusual body proportions. Despite its limitations, it provides a reliable and accessible estimate without requiring specialized equipment.
What is the difference between BMI and body fat percentage?
BMI (Body Mass Index) is a simple ratio of weight to height squared and does not distinguish between muscle and fat mass. Body fat percentage directly measures the proportion of your body that is fat tissue. A muscular athlete may have a high BMI but low body fat, while a sedentary person could have a normal BMI but high body fat. Body fat percentage gives a more accurate picture of health and fitness.
How do you measure waist circumference correctly?
Measure your waist circumference at the narrowest point of your natural waistline, typically at the level of your navel or just above it. Stand upright, breathe normally, and wrap the tape measure snugly around your bare skin without compressing it. Take the measurement at the end of a normal exhalation. For the Navy method, measure at the navel level for consistency.
Can body fat be too low?
Yes, having too little body fat is dangerous and can lead to serious health problems. Essential body fat (2-5% for men, 10-13% for women) is needed for normal physiological functions including hormone production, organ protection, temperature regulation, and vitamin absorption. Extremely low body fat can cause hormonal disruption, weakened immunity, bone loss, organ damage, and in women, loss of menstrual function.
What is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that consists of fat tissue. It is one of the most reliable indicators of overall health and fitness, often considered more meaningful than BMI alone. Body fat percentage accounts for the difference between fat mass and lean mass (muscles, bones, organs, and water).
Maintaining a healthy body fat percentage is associated with reduced risk of cardiovascular disease, type 2 diabetes, and other metabolic conditions. Ideal ranges differ between men and women due to essential fat differences required for hormonal and reproductive functions.
How to Use This Calculator
- Select your preferred unit system (Imperial or Metric).
- Choose your gender (Male or Female).
- Enter your height. For Imperial, provide feet and inches separately.
- Optionally enter your weight to compute fat mass and lean mass.
- Measure and enter your waist circumference at the narrowest point (navel level for men).
- Measure and enter your neck circumference just below the larynx.
- If female, measure and enter hip circumference at the widest point.
- Click "Calculate Body Fat" to see your results.
US Navy Method Formulas
The US Navy body fat formula uses circumference measurements and height to estimate body fat percentage. All measurements must be in centimeters for the formula. If you enter values in inches, the calculator converts them automatically.
Male Formula
BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Female Formula
BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Note: Fat mass and lean mass are derived from body fat percentage: Fat Mass = Weight × BF%, Lean Mass = Weight − Fat Mass.
Examples
Example 1: Male, Imperial
Inputs: Height 5′10″ (177.8 cm), Waist 34″ (86.4 cm), Neck 15″ (38.1 cm), Weight 180 lbs
BF% = 86.010 × log10(86.4 − 38.1) − 70.041 × log10(177.8) + 36.76 ≈ 17.7%
Fat Mass ≈ 31.9 lbs, Lean Mass ≈ 148.1 lbs
Example 2: Female, Metric
Inputs: Height 165 cm, Waist 72 cm, Neck 32 cm, Hip 98 cm, Weight 62 kg
BF% = 163.205 × log10(72 + 98 − 32) − 97.684 × log10(165) − 78.387 ≈ 24.2%
Fat Mass ≈ 15.0 kg, Lean Mass ≈ 47.0 kg
Body Fat Categories (ACE/AMA Guidelines)
| Category | Male | Female |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
These ranges follow guidelines from the American Council on Exercise (ACE) and are widely used in clinical and fitness settings.
Use Cases
- Tracking fitness progress alongside weight and strength metrics
- Setting realistic goals for fat loss or lean muscle gain
- Military and law enforcement physical readiness assessments
- Sports performance evaluation for athletes across disciplines
- Health screening to identify potential metabolic risks
Measurement Tips
- Use a flexible, non-stretchable measuring tape for consistent readings.
- Measure waist at the navel for men, or at the narrowest point for women.
- Measure neck just below the larynx (Adam's apple), keeping the tape level.
- Measure hips at the widest point of the buttocks.
- Take measurements in the morning before eating for the most consistent results.
- Do not pull the tape too tight or leave it too loose — it should be snug without compressing skin.
- For best accuracy, take each measurement two to three times and use the average.
Related Tools
- BMI Calculator — Calculate your Body Mass Index to assess healthy weight range.
- BMR Calculator — Estimate your basal metabolic rate from age, gender, height, and weight.
- TDEE Calculator — Calculate your total daily energy expenditure for weight management.
- Macro Calculator — Compute daily protein, carbs, and fat targets for your goals.
Important Health Disclaimer
This calculator is for informational and educational purposes only.
- Results are estimates and not a medical diagnosis.
- Individual factors such as medical history, medications, and pre-existing conditions can significantly affect results.
- Do not use this tool to make medical decisions on your own.
- Always consult a qualified healthcare professional for personalized medical advice, diagnosis, or treatment.