What is a body fat calculator?
A body fat calculator estimates your body fat percentage using measurements and formulas. Body fat percentage is the proportion of your total body weight that is fat tissue, as opposed to lean mass (muscle, bone, organs). Unlike BMI, which only considers weight and height, body fat percentage provides insight into body composition. This calculator uses the U.S. Navy method, which uses age, height, weight, and circumference measurements (neck, waist, and hip for women) to estimate body fat.
Enter your gender, age, height, weight, and circumference measurements (neck, waist, and hip for women), then click Get result to see your estimated body fat percentage and fitness category. No sign-up required. Use it to track fitness progress, set health goals, or understand your body composition.
How to use this body fat calculator
Select your gender (male or female—formulas differ). Enter your age in years. Enter height in centimeters, weight in kilograms. Measure and enter neck circumference (below the larynx), waist circumference (at the narrowest point, usually at navel level), and for women, hip circumference (at the widest point). Measure in the morning before eating, using a flexible measuring tape, keeping it parallel to the floor. Click Get result to see your body fat percentage and fitness category.
Understanding body fat percentage
Body fat percentage is the proportion of fat tissue in your total body weight. Essential fat is the minimum needed for normal physiological function (about 3-5% for men, 8-12% for women). Athletes typically have 6-13% (men) or 14-20% (women). Fitness level: 14-17% (men) or 21-24% (women). Average: 18-24% (men) or 25-31% (women). Obese: above 25% (men) or 32% (women). These ranges vary by age and individual factors. The calculator shows your category based on these general guidelines.
U.S. Navy method explained
The U.S. Navy method uses circumference measurements and body measurements to estimate body fat. It's convenient because it only requires a measuring tape, but it's less accurate than methods like DEXA scan or hydrostatic weighing. The formula accounts for age, height, weight, and circumference measurements. For men, it uses neck and waist. For women, it adds hip measurement. The method assumes average body fat distribution, so results may vary for individuals with atypical fat distribution patterns.
Body fat vs BMI
BMI (Body Mass Index) only considers weight and height, while body fat percentage considers body composition. Two people can have the same BMI but very different body fat percentages. For example, a muscular athlete might have a high BMI but low body fat, while someone with low muscle mass might have a normal BMI but high body fat. Body fat percentage provides more insight into health risks and fitness level, especially for athletes or people with high muscle mass. However, both are screening tools, not diagnostic.
When body fat percentage matters
Body fat percentage is useful for tracking fitness progress (muscle gain and fat loss), setting health goals, understanding health risks (very high or very low body fat can indicate health issues), and evaluating athletic performance. However, it's just one metric. Overall health depends on many factors: cardiovascular fitness, strength, flexibility, nutrition, sleep, stress management, and more. Don't obsess over a single number—focus on overall health and sustainable habits.
Limitations of body fat calculators
This calculator uses the U.S. Navy method, which is an estimate, not a precise measurement. Accuracy depends on accurate measurements and typical fat distribution. More accurate methods include DEXA scan (dual-energy X-ray absorptiometry), BodPod (air displacement plethysmography), hydrostatic weighing (underwater weighing), and bioelectrical impedance analysis (BIA). These methods are more expensive and less accessible. The calculator provides a reasonable estimate for most people, but individual results may vary.
Tips for accurate measurements
Measure in the morning before eating or drinking, after using the bathroom. Use a flexible, non-stretchy measuring tape. Measure at the same time of day for consistency. For neck: measure below the larynx, perpendicular to the neck. For waist: measure at the narrowest point (usually at navel level), or if there's no narrowest point, measure at the navel. For hip (women): measure at the widest point, usually around the buttocks. Keep the tape parallel to the floor, snug but not tight. Measure to the nearest 0.1 cm for accuracy.
Summary
This body fat calculator estimates body fat percentage using the U.S. Navy method based on age, height, weight, and circumference measurements. Enter your measurements and click Get result to see your body fat percentage and fitness category. It's free, works in your browser, and requires no account. Use it to track fitness progress or understand body composition, but remember it's an estimate. For precise measurements, consider professional methods like DEXA scan. Focus on overall health and sustainable habits rather than obsessing over a single number.