Skinfold Body Composition Test: Protocol and Formulas

If you want to know what someone's body weight is made of (fat, muscle, everything else), the skinfold test is still one of the most widely used tools in the training world. It's cheap, portable, and—if done correctly—reliable enough for tracking progress.

It won't give you the exact figure a DEXA scan would, but for 99% of cases you don't need that: what matters is the trend over time, and that's exactly where calipers shine.

What does this test measure?

The skinfold test estimates body fat percentage by measuring the thickness of subcutaneous adipose tissue at several specific points on the body. From the sum of those skinfolds (in mm), a regression formula (Jackson-Pollock, Durnin-Womersley, Faulkner, etc.) is applied to estimate body density and, from there, body fat percentage.

It doesn't directly measure visceral fat or muscle composition, but it correlates well with total body fat percentage across most populations.

Equipment needed

• Skinfold calipers: from budget-friendly options like Slim Guide to precision models like Harpenden
• Tape measure (to locate anatomical landmarks)
• Skin marker pen (optional, to mark points)
• Reference table with the chosen formula (Jackson-Pollock 3-site or 7-site is the most common)

Step-by-step protocol

1. Choose a formula based on the number of sites you'll measure (3 or 7 is most common in training settings)
2. Locate and mark the relevant anatomical landmarks. For Jackson-Pollock 3-site:

- Men: chest, abdomen, thigh - Women: triceps, suprailiac, thigh

1. Pinch the skinfold (skin + adipose tissue, no muscle) between thumb and index finger, 1 cm from the marked point
2. Place the caliper jaws perpendicular to the fold, 1 cm from your fingers, and read the value 1-2 seconds after applying pressure
3. Repeat 2-3 times per site and use the average (or the median if one reading is an outlier)
4. Sum the skinfolds and apply the corresponding formula to get the body fat percentage

Common mistakes

• Measuring over clothing or sweaty skin (alters the thickness reading)
• Pinching muscle along with skin and fat
• Switching evaluators between assessments without cross-training (inter-evaluator variability is the main source of error)
• Not always measuring on the same side of the body

How to interpret the result

Body fat %	Men	Women
Essential	2-5%	10-13%
Athletic	6-13%	14-20%
Fitness/Healthy	14-17%	21-24%
Acceptable	18-24%	25-31%
Obesity	≥25%	≥32%

Reference values based on American Council on Exercise (ACE) ranges. They may vary depending on formula and age.

Relationship with other tests

The body fat percentage you get from skinfolds is most useful when combined with:

• Bioimpedance test — a second reference point to spot large discrepancies between methods
• Body circumference test — to understand where that fat is being gained or lost

Track progress without losing data

The biggest challenge with skinfolds isn't the measurement itself—it's maintaining consistency over months: same sites, same side, same evaluator whenever possible. With Movalytics you can log each individual skinfold (not just the final result), choose your calculation formula, and watch your client's body fat percentage evolve in a chart, session by session, without redoing calculations by hand every time.

Frequently asked questions

What's the most accurate skinfold formula? There's no universal "best" one: Jackson-Pollock works well for trained general populations, while Durnin-Womersley covers broader age ranges. What matters most is always using the same formula so comparisons over time remain valid. How often should this test be repeated? Every 4-6 weeks is reasonable to see real changes without measurement "noise" (hydration, time of day) distorting the trend. Can I measure my own skinfolds? Some sites (triceps, abdomen) can be self-measured, but reliability drops significantly. Ideally, the same trained person should always take the measurements.