Body Fat Calculator
Estimate your body fat percentage using your height, neck, waist, and hip measurements. Choose your unit system and get a clear result with a step-by-step calculation.
Calculate Body Fat Percentage
Enter your measurements below. The calculator uses a circumference-based body fat estimation formula. Women also need to enter hip circumference.
How the Body Fat Calculator Works
This calculator estimates body fat percentage from height and body circumference measurements. The calculation uses logarithmic equations and requires different measurements for men and women.
Men use height, neck circumference, and waist circumference. Women also use hip circumference.
Body Fat % = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women
Body Fat % = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
The original equations use inches for height and circumference measurements. When Metric is selected, the calculator converts the entered measurements to inches before applying the equations.
Step-by-step
How to Measure for the Calculator
Height
Measure your standing height without shoes. Keep your body upright and use the same unit selected in the calculator.
Neck
Measure around your neck using a flexible measuring tape. Keep the tape comfortably positioned rather than pulling it tightly.
Waist
Measure your waist circumference consistently and keep the measuring tape level. Avoid compressing the skin with the tape.
Hips
Women should also measure around the widest part of the hips.
For consistent tracking, take measurements under similar conditions each time.
Body Fat Calculator Example
Suppose a man is 69 inches tall, has a 16-inch neck, and a 49-inch waist.
Related calculators
Body Fat Calculator FAQs
Is this body fat calculator accurate?
This calculator provides an estimate based on body circumference measurements. It should not be treated as a direct measurement of body fat or as a medical diagnosis.
Why does the calculator use log₁₀?
The body-fat equations are logarithmic regression equations. The logarithm used in these equations is base 10, written as log₁₀.
Can I use centimeters?
Yes. Select Metric (cm). FreeCalz converts the measurements to inches internally before applying the equations.
Why do women need a hip measurement?
The female equation includes waist, hip, and neck circumference, while the male equation uses waist and neck circumference.
Is body fat percentage the same as BMI?
No. BMI is calculated from height and weight, while body fat percentage estimates the proportion of body weight that is fat. They measure different aspects of body composition.
Important: This calculator provides an estimated body fat percentage for informational and educational purposes. It is not a medical diagnosis or a substitute for professional body-composition assessment. Results can vary because of measurement technique, body shape, hydration, and the estimation method used. Do not use the result alone to make medical or health decisions.