Durnin-Womersley Body Fat Calculator
Estimate body fat from four skinfolds — biceps, triceps, subscapular and suprailiac — with the Durnin-Womersley (1974) age- and sex-specific equations and the Siri formula.
How it works
S = biceps + triceps + subscapular + suprailiac (mm) · BD = c − m × log₁₀(S), with c and m by age group and sex (Durnin & Womersley 1974) · %BF = 495 ÷ BD − 450 (Siri)
Durnin and Womersley measured 481 men and women aged 16 to 72 in Glasgow and published equations that convert the logarithm of four skinfolds into body density, with separate constants for each age decade and sex. Because the sites are all on the arm and trunk, the method is quick and does not require undressing the legs; it remains one of the most-cited skinfold methods in nutrition and clinical research.
Worked example
A 25-year-old man with biceps 6, triceps 12, subscapular 14 and suprailiac 16 mm (sum 48 mm): log₁₀ 48 = 1.6812, so BD = 1.1631 − 0.0632 × 1.6812 = 1.0568 g/cm³ and body fat = 495 ÷ 1.0568 − 450 = 18.4% — the ACE Average category.
Frequently asked questions
Where are the four Durnin-Womersley sites?
Biceps (vertical fold on the front of the upper arm, mid-way), triceps (vertical, back of the upper arm, mid-way), subscapular (diagonal, just below the shoulder blade) and suprailiac (diagonal, just above the iliac crest on the mid-axillary line).
How accurate is the Durnin-Womersley method?
Against underwater weighing the standard error is about 3.5–5% body fat, similar to other skinfold equations. It tends to overestimate fat in very lean athletes.
Why does age change the result?
With age, a larger share of body fat is stored internally rather than under the skin, so the same skinfold total means more total fat. The equations have different constants for each decade to account for this.
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This calculator gives an estimate for general fitness and education only. It is not a diagnosis — results from field tests and prediction equations can differ from laboratory measurements, so talk to a doctor or qualified exercise professional before acting on them.