Body Fat Calculator
Estimate your body fat percentage using the US Navy method and BMI-based formula
Your age affects ideal body fat ranges and the BMI-based estimate
Used to calculate fat mass and lean body mass
Use a flexible tape measure. Keep the tape snug but not compressing the skin.
Measure just below the larynx (Adam's apple), tape sloping slightly downward at the front
Men: measure at navel level. Women: measure at the narrowest point
Calculate Your Body Fat
Enter your measurements above to see your body fat percentage, category, and detailed body composition breakdown.
How to Use the Body Fat Calculator
Select Your Gender and Enter Your Age
Choose male or female and enter your age in years. Gender determines which formula variant is used and whether hip circumference is required. Age is used for the BMI-based estimate and ideal body fat range.
Choose Units and Enter Weight and Height
Select US (pounds, inches) or Metric (kilograms, centimeters) units. Enter your current weight and height. These are used to calculate BMI, fat mass, and lean body mass breakdown.
Take and Enter Body Measurements
Using a flexible tape measure, measure your neck circumference just below the Adam's apple, your waist at navel level (men) or narrowest point (women), and your hip at the widest point (women only). Keep the tape snug but not tight.
Review Your Results
Click Calculate to see your body fat percentage from both the US Navy and BMI methods, your ACE category with health context, fat vs lean mass breakdown, ideal range for your age and gender, and a visual gauge showing where you fall on the body fat spectrum.
Frequently Asked Questions
How accurate is the US Navy body fat method?
The US Navy circumference method has been validated against hydrostatic weighing and DEXA scans, with typical accuracy within 3-4 percentage points for most individuals. It performs best for people in the normal to moderately overweight range. The accuracy depends heavily on correct measurement technique, so use a flexible tape measure, keep it level and snug without compressing the skin, and take measurements at the same time of day for consistency. For very lean or very obese individuals, the formula may be less accurate. Clinical methods like DEXA scanning or hydrostatic weighing provide greater precision but require specialized equipment and professional supervision.
Why does the calculator need different measurements for men and women?
Men and women store body fat differently due to hormonal differences. Women tend to carry more fat in the hips, thighs, and breasts, which is why hip circumference is required for the female formula. The US Navy formula accounts for these biological differences by using separate equations. For men, the formula uses waist and neck circumference relative to height. For women, it adds hip circumference to capture the additional fat storage sites. Women also have higher essential fat requirements (10-13% versus 2-5% for men) because fat plays critical roles in reproductive health, hormone production, and organ protection. The ACE body fat categories reflect these differences with separate ranges for each gender.
What is a healthy body fat percentage for my age?
Healthy body fat ranges increase gradually with age as the body naturally accumulates more fat and loses some muscle mass. For men aged 20-29, a healthy range is 11-17%; ages 30-39, 12-19%; ages 40-49, 14-21%; ages 50-59, 15-22%; and 60+, 16-23%. For women aged 20-29, a healthy range is 16-24%; ages 30-39, 17-25%; ages 40-49, 19-27%; ages 50-59, 20-28%; and 60+, 21-29%. These ranges correspond roughly to the Fitness and Acceptable ACE categories. Athletes and very active individuals may be below these ranges, which is healthy for them. Consistently being above the upper range for your age group indicates increased health risk.
Why is my BMI-based estimate different from the Navy method result?
The two methods use fundamentally different inputs, so some variation is expected. The Navy method measures actual circumferences that reflect where fat is stored, while the BMI-based formula only uses height, weight, age, and gender. BMI cannot distinguish between muscle and fat, so muscular individuals often get inflated BMI-based body fat estimates. Conversely, people with low muscle mass (sometimes called skinny fat) may get a lower BMI-based estimate than their actual body fat. The Navy method is generally more accurate because circumference measurements capture body composition information that BMI misses. If the two estimates differ significantly, the Navy method result is usually more reliable.
How often should I measure my body fat, and how can I reduce it?
Measure your body fat no more than once every two to four weeks. Body composition changes slowly, and daily or weekly measurements are influenced by hydration, food intake, and measurement variation, which can be discouraging. To reduce body fat while preserving muscle, maintain a moderate caloric deficit of 300-500 calories below your maintenance level. Eat adequate protein (0.7-1 gram per pound of body weight) to support muscle retention. Prioritize resistance training three to four times per week, as building and maintaining muscle increases your metabolic rate. Add moderate cardio for additional calorie burn. Avoid crash diets, which cause muscle loss and metabolic slowdown. Aim for 0.5-1 pound of fat loss per week for sustainable, long-term results.