Skinfold Body Fat
Calculate your body fat percentage using the Durnin-Womersley 4-site skinfold method. Free online calculator with body density, fat mass, lean mass, and fitness level classification.
Skinfold Measurements (mm)
About This Calculator
The Skinfold Body Fat Calculator estimates your body fat percentage using the validated Durnin-Womersley 4-site skinfold method, one of the most widely used field techniques for body composition assessment. By measuring subcutaneous fat thickness at four standard sites — bicep, tricep, subscapular, and suprailiac — this calculator provides accurate estimates of body density, body fat percentage, fat mass, and lean body mass using age- and sex-specific regression equations.
The Durnin-Womersley method works by first calculating body density from the log10 of the sum of four skinfold measurements using equations developed from a large reference population. The body density is then converted to body fat percentage using the Siri equation: body fat % = (495 / body density) — 450. Because body fat distribution and density vary by age and gender, separate regression coefficients are used for males and females across six age groups (under 17, 17-19, 20-29, 30-39, 40-49, and 50+).
How to take accurate skinfold measurements
For best results, use a calibrated skinfold caliper and measure on the right side of the body. Pinch the skinfold firmly between thumb and forefinger about 1 cm above the measurement site, pull the fold away from the underlying muscle, and place the caliper jaws perpendicular to the fold. Read the measurement to the nearest 0.5 mm after 2 seconds. Repeat each site twice and use the average. All measurements should be taken in millimeters.
Regional notes
Body fat percentage norms and health categories are consistent across IN, US, and UK populations, with the same ACE/WHO classification criteria applied globally. The Durnin-Womersley equations were developed on a Caucasian population; accuracy may vary for other ethnicities. For individuals of Asian descent, alternative formulas such as the Wang or Gallagher equations may be more appropriate. Always consult a healthcare professional for a comprehensive body composition assessment.
Frequently Asked Questions
How does the skinfold body fat calculator work?
The skinfold body fat calculator uses the Durnin-Womersley method, which calculates body density from the log of the sum of four skinfold measurements (bicep, tricep, subscapular, suprailiac) using age- and sex-specific regression equations, then converts body density to body fat percentage using the Siri equation: body fat % = (495 / body density) — 450.
How do I measure skinfolds with a caliper?
Pinch the skin at the measurement site using your thumb and index finger, gently pull the skinfold away from the muscle, place the caliper perpendicular to the fold about 1 cm from your fingers, and read the thickness in millimeters after 2 seconds. Take two measurements at each site for accuracy.
What are the four skinfold measurement sites?
The four sites are: bicep (midpoint between shoulder and elbow over the bicep muscle, vertical fold), tricep (midpoint between shoulder and elbow over the tricep muscle, vertical fold), subscapular (just below the bottom tip of the shoulder blade at a 45-degree angle), and suprailiac (just above the hip bone along the mid-axillary line at a 45-degree angle).
Is the Durnin-Womersley skinfold method accurate?
The Durnin-Womersley 4-site skinfold method has an accuracy of approximately ±3.5% when performed correctly by a trained practitioner. It is a validated and widely used field method for estimating body composition but may be less accurate than laboratory methods such as DEXA, hydrostatic weighing, or air displacement plethysmography.
What is a healthy body fat percentage?
For men, essential fat is 2-5%, athlete 6-13%, fitness 14-17%, average 18-24%, and obese 25%+. For women, essential fat is 10-13%, athlete 14-20%, fitness 21-24%, average 25-31%, and obese 32%+. These ranges vary slightly by age and source.
Why does the calculator need my age and gender?
The Durnin-Womersley equations use different regression coefficients for males and females across six age groups because body density and fat distribution patterns change with age and differ between sexes. Using the correct age and gender ensures accurate body density and body fat percentage calculations.
What is body density and how is it calculated?
Body density is calculated by subtracting the product of the age- and sex-specific slope coefficient and the log10 of the sum of four skinfolds from the age- and sex-specific intercept coefficient. Body density is expressed in g/cm³ and is then used in the Siri equation to estimate body fat percentage.
Can I use this calculator to track fitness progress?
Yes. The skinfold body fat calculator is an excellent tool for tracking changes in body composition over time. Taking measurements at consistent sites every 4-6 weeks using the same caliper and technique allows you to monitor fat loss and muscle gain trends with your personal data.