Body Fat Calculator
Estimate your body fat percentage using your age, sex, height, and body circumference measurements with a commonly used circumference-based method.
Calculate your body fat percentage
Select your sex and enter your measurements below. Use a flexible measuring tape and measure consistently.
Your result
—
| Sex | — |
| Age | — |
| Height | — |
| Neck circumference | — |
| Waist / abdominal circumference | — |
| Estimated body fat | — |
Step-by-step calculation
What does the result mean?
Body fat percentage represents the estimated proportion of your total body weight that is fat.
Body fat percentage is different from BMI. BMI uses height and weight, while body fat estimation attempts to account for body composition.
Circumference-based calculations provide estimates and can be affected by measurement technique, body shape, tape placement, and other factors.
How is body fat calculated?
This calculator uses a circumference-based estimation approach. Measurements are converted to inches and used with sex-specific equations.
Men use height, neck circumference, and abdominal circumference. Women use height, neck circumference, natural waist circumference, and hip circumference.
The current U.S. Navy body-composition guidance also emphasizes consistent measurement technique and treats the resulting percentage as an estimate rather than a direct measurement. :contentReference[oaicite:1]{index=1}
Body fat calculator example
Suppose a 30-year-old male is 175 cm tall, with a neck circumference of 38 cm and an abdominal circumference of 85 cm.
Neck = 38 cm ÷ 2.54 = 14.96 inches
Abdomen = 85 cm ÷ 2.54 = 33.46 inches
The converted measurements are then used in the male circumference-based body-fat equation.
The final percentage is an estimate and may differ from results obtained using other body-composition methods.
Formula used
Body Fat % = 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76
Women:
Body Fat % = 163.205 × log₁₀(waist + hips − neck) − 97.684 × log₁₀(height) − 78.387
Measurements in these equations are expressed in inches. The equations are intended to provide an estimate and are not a direct measurement of body fat.
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Important: This calculator provides an estimated body fat percentage for general informational purposes only. Circumference-based estimates can differ from direct body-composition measurements and may be affected by measurement technique, body shape, hydration, and other factors. The result should not be used to diagnose a medical condition or make medical decisions. If you have concerns about your body composition, weight, nutrition, or health, consult a qualified healthcare professional.