Body Fat Percentage Calculator

Estimate your body fat percentage using the U.S. Navy method or BMI-based method. This tool processes all data locally in your browser. No information is ever sent to any server. Completely free, no registration required.

How to Use the Body Fat Percentage Calculator

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Body Fat Percentage Calculator?

A Body Fat Calculator estimates the percentage of your total body weight that comes from fat tissue versus lean mass (muscle, bones, organs, water). Unlike BMI, which only uses height and weight, body fat percentage is a far more meaningful indicator of fitness and health. The American Council on Exercise classifies body fat ranges: Essential Fat (2-5% men, 10-13% women), Athletes (6-13% men, 14-20% women), Fitness (14-17% men, 21-24% women), Average (18-24% men, 25-31% women), and Obese (25%+ men, 32%+ women). This calculator uses the US Navy method (neck, waist, and hip measurements) and the skinfold method for accurate estimates without expensive DEXA scans.

How Does It Work?

Our calculator supports two evidence-based methods. The US Navy method uses circumference measurements: for men, measure neck and waist at the navel; for women, measure neck, waist, and hips. The formula was developed from large-scale military anthropometric data. Enter your measurements in inches or centimeters, and the calculator instantly returns your body fat percentage and fitness category. For best accuracy, measure first thing in the morning before eating, with a flexible (but not stretchy) measuring tape.

Formula

US Navy Method (Men): Body Fat% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76\nUS Navy Method (Women): Body Fat% = 163.205 × log₁₀(waist + hips − neck) − 97.684 × log₁₀(height) − 78.387\n\nBMI Method (approximate):\nMen: Body Fat% = (1.20 × BMI) + (0.23 × Age) − 16.2\nWomen: Body Fat% = (1.20 × BMI) + (0.23 × Age) − 5.4

Who Uses This Tool?

• Fitness enthusiasts tracking body composition changes during a cut/bulk cycle
• Personal trainers establishing client baselines and measuring progress
• Health-conscious individuals getting a more complete picture than BMI alone
• Athletes aiming for sport-specific body fat targets
• Weight loss patients tracking fat loss vs. muscle loss

Pro Tips

• The US Navy method is typically accurate within 3-4% of DEXA scan results. For best results, have someone else take your measurements — self-measuring introduces error
• Measure at the same time of day, preferably morning, for consistent tracking. Body fat readings can vary 1-2% throughout the day due to hydration
• Don't obsess over daily readings — body fat changes slowly. Track weekly or bi-weekly for meaningful trends
• Combine body fat percentage with waist-to-hip ratio for a comprehensive health risk assessment

Frequently Asked Questions about Body Fat Percentage Calculator

What's a healthy body fat percentage?

For men, 10-20% is generally healthy; for women, 18-28%. However, healthy ranges vary by age. Athletes typically have lower percentages. Essential fat (minimum for basic health) is 2-5% for men and 10-13% for women.

Is the US Navy method accurate?

Research shows the Navy method is accurate within 3-4% of DEXA (the gold standard) for most people. It's more accurate than BMI for individuals with higher muscle mass. Accuracy decreases for extremely lean or obese individuals.

How do I reduce body fat percentage?

Sustain a moderate calorie deficit (300-500 calories/day below maintenance), prioritize protein intake (0.7-1g per pound of body weight), do resistance training 3-4×/week to preserve muscle, and get adequate sleep. Aim for 0.5-1% body fat loss per week.

Free online Body Fat Percentage Calculator — no signup, 100% client-side processing. All data stays in your browser.