Skip to main content

Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy method with our free calculator. Enter your measurements to get body fat %, fat mass, lean mass, and your body composition category.

Loading calculator

Preparing Body Fat Calculator...

Reviewed & Methodology

Every calculator is built using industry-standard formulas, validated against authoritative sources, and reviewed by a credentialed financial professional. All calculations run privately in your browser - no data is stored or shared.

Last reviewed:

Reviewed by:

Written by:

Read Methodology Report an Issue

How to Use the Body Fat Calculator

  1. 1. Select your gender - body fat formulas differ for men and women due to different fat distribution patterns.
  2. 2. Enter your height - input your height in feet/inches or centimeters.
  3. 3. Enter circumference measurements - measure your waist at the navel, neck at the narrowest point, and (for women) hips at the widest point using a cloth tape measure.
  4. 4. Enter your weight - input your current weight to calculate fat mass and lean mass in pounds or kilograms.
  5. 5. Review your results - see your body fat percentage, category (essential, athlete, fit, average, or obese), fat mass, and lean mass.

Body Fat Calculator

Estimate your body fat percentage in seconds using the U.S. Navy method. This calculator uses your height, waist, neck, and hip measurements to determine body fat percentage, fat mass, and lean mass — giving you a clearer picture of your body composition than weight alone.

How Body Fat Is Calculated

The U.S. Navy method uses a logarithmic formula based on circumference measurements. For men: BF% = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women, hip circumference is added: BF% = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. All measurements are in inches.

Example

GenderHeightWaistNeckWeightBody Fat %Category
Male5’10”34 in15 in180 lbs~18.0%Average
Male5’10”32 in15.5 in170 lbs~14.5%Fit
Female5’5”30 in13 in145 lbs~24.0%Fit

Key Factors That Affect Body Fat

  • Waist circumference — the single biggest variable; measure at the navel for consistency
  • Neck size — a thicker neck relative to waist lowers the calculated percentage
  • Height — taller individuals tend to get slightly lower readings at the same waist size
  • Gender — women carry essential fat in hips and breasts, so healthy ranges are higher (14-25%) than men (6-18%)
  • Measurement accuracy — even half an inch of error can shift results by 1-2 percentage points

Tips

  1. Measure at the same time of day (morning, before eating) for consistent tracking over time
  2. Use a flexible cloth tape measure and keep it snug but not compressing the skin
  3. For women, always include the hip measurement taken at the widest point of the buttocks
  4. Compare results across several weeks rather than day-to-day to see meaningful trends

Frequently Asked Questions

What is a healthy body fat percentage for men and women?
Healthy body fat ranges differ significantly by gender. For men, 6-13% is considered athletic, 14-17% is fit, 18-24% is average, and above 25% is obese. For women, 14-20% is athletic, 21-24% is fit, 25-31% is average, and above 32% is obese. Women require higher essential fat (10-13%) compared to men (2-5%) due to reproductive and hormonal functions. These ranges shift slightly with age -- older adults can carry a few percentage points more and still be considered healthy.
How accurate is the U.S. Navy body fat method compared to other methods?
The Navy method is accurate within 3-4% of DEXA scan results for most people, making it one of the best non-invasive estimation techniques. It is more reliable than single-site skinfold calipers but less precise than hydrostatic weighing or DEXA scans. Its main advantage is accessibility -- you only need a tape measure. For the most accurate Navy method results, take measurements at the same time of day and ensure consistent tape placement.
What is the difference between essential fat and storage fat?
Essential fat is the minimum amount of body fat needed for basic physiological functions including hormone production, organ insulation, and nervous system function. Men need at least 2-5% essential fat, and women need 10-13%. Storage fat is additional fat stored beneath the skin (subcutaneous) and around organs (visceral) as energy reserves. Dropping below essential fat levels is dangerous and can cause hormonal disruption, immune suppression, and organ damage.
How does age affect body fat percentage?
Body fat naturally increases with age even if weight stays the same, primarily due to declining muscle mass (sarcopenia) and hormonal changes. Between ages 20 and 60, men typically gain 1-2% body fat per decade, and women gain 1-3% per decade, particularly after menopause. A 25-year-old man at 15% body fat and a 55-year-old man at 20% can both be considered healthy for their respective age groups.
Why is body fat percentage more useful than BMI?
Body fat percentage directly measures your ratio of fat to total body weight, while BMI only uses height and weight without distinguishing muscle from fat. A 200-pound person at 12% body fat has a very different health profile than a 200-pound person at 35% body fat, even if they are the same height. Body fat percentage also better tracks fitness progress -- you might gain muscle and lose fat while your weight (and BMI) stays unchanged, but your body fat percentage would improve.

Explore More Health & Fitness Tools

BMI Calculator: Try our free bmi calculator for instant results.

Calorie Calculator: Try our free calorie calculator for instant results.

Heart Rate Calculator: Try our free heart rate calculator for instant results.

Health Insurance Calculator: Try our free health insurance calculator for instant results.

Disability Insurance Calculator: Try our free disability insurance calculator for instant results.

Life Insurance Calculator: Try our free life insurance calculator for instant results.

Related Health & Fitness Calculators

Health & Fitness

Blood Alcohol Calculator

Estimate your blood alcohol concentration (BAC) with our free calculator. Enter your weight, gender, number of drinks, and time elapsed to see your estimated BAC level, impairment effects, and approximate time until sober. For educational purposes only.

Health & Fitness

BMI Calculator

Calculate your Body Mass Index (BMI) instantly with our free online BMI calculator. Enter your height and weight to see your BMI category, healthy weight range, and what your results mean for your health.

Health & Fitness

Body Surface Area Calculator

Calculate your body surface area (BSA) using multiple formulas with our free calculator. Enter your height and weight to see BSA results from the Du Bois, Mosteller, Haycock, and Gehan-George methods, used in drug dosing, burn assessment, and clinical medicine.

Health & Fitness

Calorie Calculator

Calculate your daily calorie needs with our free calorie calculator. Uses the Mifflin-St Jeor equation to estimate BMR, maintenance calories, and targets for weight loss or gain based on your age, gender, height, weight, and activity level.

Calculators