Body Fat Percentage Calculator

Body fat percentage describes the share of total body mass made up of fat tissue. Unlike BMI, which compares only weight and height, a body fat estimate aims to distinguish fat from lean tissue. This calculator uses the U.S. Navy circumference method because it requires only a tape measure. It combines height, waist, and neck for men, and adds hip circumference for women. The published equations use logarithms of measurements in inches; centimetre entries are converted internally before calculation. Measurement technique strongly affects the result. Use a non-stretch tape against the skin without compressing tissue. Keep the tape level and measure under similar conditions each time. The waist and neck sites should follow the protocol being used, and hip circumference should capture the widest point. Take two or three readings and repeat when they differ noticeably. Hydration, breathing, posture, recent meals, and tape placement can all introduce variation larger than a small apparent change. No field method is perfectly accurate. Circumference equations were developed from population data and may be less representative for some ages, body shapes, ethnic groups, athletes, or people with substantial muscle mass. Skinfold calipers, bioelectrical impedance scales, air-displacement plethysmography, hydrostatic weighing, and DEXA each use different assumptions and have their own error ranges. Results from different methods should not be treated as interchangeable. For tracking, use the same method, conditions, and equipment and focus on a trend over time. Body fat supports hormones, insulation, organ protection, and energy storage, so lower is not always healthier. Appropriate ranges differ with sex, age, athletic demands, pregnancy, and medical context. A single percentage does not assess cardiovascular fitness, strength, nutrition, blood pressure, laboratory markers, or mental wellbeing. Avoid using the result to justify severe dieting or dehydration. If body composition is important for medical care, sport eligibility, or treatment, request a validated professional assessment. People with concerns about growth, menstrual function, eating behavior, or unexplained physical change should speak with a clinician. This calculator offers a convenient educational estimate and should be interpreted alongside broader health information.