Durnin–Womersley Body-Fat Calculator
Use this Durnin–Womersley body-fat calculator to estimate body-fat percentage from four skinfold readings, age and sex.
Enter biceps, triceps, subscapular and suprailiac readings in millimeters. The calculator uses the age group that applies to the sex and completed age you choose.
See your estimated body-fat percentage and how nearby caliper readings change it. Add bodyweight for estimated fat mass and fat-free mass, meaning the rest of your bodyweight after estimated fat mass, then save a baseline for your next measurement.
Read your Durnin–Womersley estimate
Your result uses four caliper readings and the Durnin–Womersley age group that matches your sex and completed age. Keep the selected sex, age and four millimeter readings with the percentage when you save or compare it.
The age group used for your estimate comes from your sex and completed age. The calculator does not interpolate between groups.
Calculate above to see your estimate, age group and readings.
Take the four caliper readings consistently
Record biceps, triceps, subscapular and suprailiac skinfolds in millimeters (mm). This is a four-site protocol for people who can repeat all four landmarks with the same side, tester and caliper timing.
- Biceps
- Over the belly of the biceps on the front of the upper arm.
- Triceps
- Halfway between the shoulder and elbow on the back of the upper arm.
- Subscapular
- Just below the lower tip of the shoulder blade, with the fold about 45 degrees to vertical.
- Suprailiac
- Just above the hipbone on the mid-axillary line, down the middle of the armpit.
- Reading units
- Record every skinfold in millimeters (mm).
For Durnin–Womersley, the suprailiac site is above the hipbone along the middle of the armpit. Jackson–Pollock uses a site farther toward the front of the body, so take a separate reading rather than reusing this one.
See how the four-site sum changes the estimate
Before you calculate, the chart shows an example. After you calculate, it updates to your selected sex, completed age, age group and readings. Nearby readings show sensitivity to measurement changes; they do not predict your true body-fat range or provide a confidence interval.
| Input or result | Value |
|---|---|
| 30 mm four-site sum | 16.1699% body fat |
| 35 mm four-site sum | 17.7743% body fat |
| 40 mm four-site sum | 19.1730% body fat |
| 45 mm four-site sum | 20.4137% body fat |
| 50 mm four-site sum | 21.5292% body fat |
Follow the Durnin–Womersley and Siri calculation
The calculator adds the four readings and converts that total into an estimated body-fat percentage. The named source coefficients and conversion details are available below.
See the calculation details
In BD = c − m × log10(total skinfold), c is the intercept for the published sex and age group and m is the coefficient multiplied by the base-10 logarithm of the four-site sum. The source age groups are 17–19, 20–29, 30–39, 40–49 and 50–72 for men, and 16–19, 20–29, 30–39, 40–49 and 50–68 for women. These are source population limits, not health recommendations.
| Sex | Source age group | c | m |
|---|---|---|---|
| Male | 17–19 | 1.1620 | 0.0630 |
| Male | 20–29 | 1.1631 | 0.0632 |
| Male | 30–39 | 1.1422 | 0.0544 |
| Male | 40–49 | 1.1620 | 0.0700 |
| Male | 50–72 | 1.1715 | 0.0779 |
| Female | 16–19 | 1.1549 | 0.0678 |
| Female | 20–29 | 1.1599 | 0.0717 |
| Female | 30–39 | 1.1423 | 0.0632 |
| Female | 40–49 | 1.1333 | 0.0612 |
| Female | 50–68 | 1.1339 | 0.0645 |
| Input or result | Value |
|---|---|
| Selected method | Durnin–Womersley four-site |
| Required sites | Biceps, triceps, subscapular and suprailiac |
| Skinfold units | Millimeters (mm) |
| Density output | Shown to 7 decimal places |
| Body-fat conversion | Siri: 100 × (4.95 ÷ density − 4.50) |
| Optional fat mass | Bodyweight × body-fat percentage ÷ 100 |
| Optional fat-free mass | Bodyweight − estimated fat mass |
Check a complete male four-site example
This checked example uses a 30-year-old man with 10 mm readings at the biceps, triceps, subscapular and suprailiac sites. The selected sum is 40 mm and the male 30–39 age group is used.
| Input or result | Value |
|---|---|
| Sex and age | Male, 30 years |
| Selected sites | Biceps 10 mm + triceps 10 mm + subscapular 10 mm + suprailiac 10 mm |
| Skinfold sum | 40 mm |
| Selected coefficient group | Male 30–39 |
| Estimated body density | 1.0550479 |
| Estimated body fat | 19.17% |
| Optional bodyweight | 80 kg |
| Estimated fat mass | 15.34 kg |
| Estimated fat-free mass | 64.66 kg |
The numbers are an illustrative calculation from the named equation and are not a target or a claim about measurement accuracy.
Understand the method limits
Durnin–Womersley equations estimate body density from caliper readings. Technique, tester skill, caliper timing, site placement and the source population affect the result. A different site protocol should be kept as a separate method.
The 1974 paper reports measurements on 481 people: 209 men and 272 women. The youngest male group is 17–19; there is no male under-17 coefficient group. The female table begins at 16–19 and ends at 50–68. The calculator preserves those boundaries.
- Durnin and Womersley (1974) — body density measurements and four-site coefficient table for men and women.
- Siri conversion: body-fat percentage = 100 × (4.95 ÷ density − 4.50), applied after the named density equation.