durnin womersley calculator

What is the Durnin-Womersley method?

The Durnin-Womersley method is a classic skinfold-based equation used to estimate body density, then convert that density into body fat percentage. It is widely used in fitness, sports science, and field testing because it only requires calipers, basic training, and four anatomical skinfold sites.

This calculator uses the original age- and sex-specific regression constants and then applies the Siri conversion formula: Body Fat % = (495 / Body Density) - 450.

How this calculator works

Step 1: Add the 4 skinfolds

• Biceps
• Triceps
• Subscapular
• Suprailiac

The sum of these four skinfolds (in mm) is transformed using log10. The result is entered into an age/sex equation to estimate body density.

Step 2: Convert body density to body fat percentage

Once density is known, Siri’s equation is used to estimate body fat percentage. If you enter body weight, this page also estimates fat mass and lean mass.

How to measure skinfolds correctly

• Measure on the right side of the body (standard practice).
• Take measurements at consistent landmarks.
• Pinch skinfold firmly, place calipers ~1 cm below fingers.
• Read caliper value after 1-2 seconds, not immediately.
• Repeat each site and average the readings.

Consistency matters more than perfection. Small technical errors can cause noticeable shifts in calculated body fat.

Interpreting your result

Body fat percentage is a useful trend metric, not a diagnosis. Compare your result with prior measurements taken under similar conditions (same time of day, hydration, and measurement technique).

General category ranges used in this calculator

• Men: Essential (2-5), Athletes (6-13), Fitness (14-17), Average (18-24), Obese (25+)
• Women: Essential (10-13), Athletes (14-20), Fitness (21-24), Average (25-31), Obese (32+)

Limitations and best practices

The Durnin-Womersley formula is validated for population-level use and practical individual tracking, but all body composition tools have error margins. Results can differ from DXA, hydrostatic weighing, BIA scales, and other models because each method uses different assumptions.

• Use the same calipers each time.
• Track trends over weeks, not day-to-day noise.
• Pair body fat data with waist, performance, and health markers.

If you need clinical-grade assessment, work with a qualified professional and lab-based methods.