Skinfold assessment is a practical body composition method that estimates subcutaneous fat thickness at selected body sites. A 4-site skinfold test uses four measured sites to provide a simple and repeatable way to monitor changes in body composition over time.
One of the most widely recognised 4-site methods is the Durnin and Womersley approach, which uses the biceps, triceps, subscapular and suprailiac skinfolds. These values can be summed to track total skinfold change or entered into age- and sex-specific equations to estimate body density and body fat percentage.
For Measurz users, the most practical value of skinfold testing is usually progress tracking. The same sites, same side, same calipers, same technique and same assessor should be used wherever possible. This makes the result more useful when comparing change over time.
Skinfold testing should be interpreted carefully. It estimates subcutaneous fat thickness, not total health, fitness, performance or body composition on its own. Skinfold equations are population-specific and may be less accurate for some clients, including very lean athletes, people with higher body fat levels, older adults, adolescents or people outside the population used to create the equation.
Skin Folds (4 Sites) is a body composition assessment that measures skinfold thickness at four standard body locations.
The common Durnin and Womersley 4-site method uses:
Biceps
Triceps
Subscapular
Suprailiac
Each site is measured with skinfold calipers and recorded in millimetres. The four values can be added together to create a sum of 4 skinfolds.
This sum can be used in two main ways:
To track change over time
To estimate body density and body fat percentage using an appropriate equation
For many Measurz workflows, tracking the sum of skinfolds is often more practical and less misleading than focusing only on a body fat percentage estimate.
A 4-site skinfold assessment may be used to:
Record baseline skinfold thickness
Track changes in subcutaneous fat over time
Support body composition monitoring
Add context to weight and girth changes
Support health, fitness, sport and performance profiling
Monitor training or nutrition-related changes where appropriate
Compare skinfold changes alongside strength, endurance and performance data
Provide a simple, low-cost field-based body composition measure
Create more detailed Measurz body measurement reports
Skinfolds can be useful when body weight alone does not tell the full story. For example, weight may remain stable while skinfolds reduce and strength improves, suggesting a different interpretation than weight alone would provide.
A 4-site skinfold assessment measures the thickness of a double layer of skin and subcutaneous tissue at selected body sites.
It may provide useful information about:
Subcutaneous fat thickness at specific sites
Sum of 4 skinfolds
Change in skinfold thickness over time
Body composition trends
How body composition changes relate to weight, girths and performance
Estimated body density or body fat percentage if a validated equation is used
It does not directly measure:
Total body fat with perfect accuracy
Visceral fat
Muscle mass
Strength
Fitness
Health status
Hydration status
Injury status
Readiness for sport or work
Performance capacity
Skinfolds are best interpreted as one part of a broader body measurement and performance profile.
To measure 4-site skinfolds in Measurz, you will need:
Skinfold calipers
Measurz app
Selected Skin Folds (4 Sites) assessment
Skin-safe marker
Flexible tape measure if landmarking is required
Consistent testing side
Private and comfortable testing environment
Notes field for recording site, side, assessor and conditions
Professional skinfold calipers are preferred because lower-quality calipers may affect measurement consistency.
Explain the purpose of the assessment clearly.
A useful explanation is:
“We are going to measure skinfold thickness at four body sites. This can help track changes in subcutaneous fat over time. It does not measure health or performance by itself, but it can add useful context when compared with your other results.”
Make sure the client is comfortable and understands the process. Skinfold testing involves contact with body sites, so consent, privacy and professional communication are important.
Before testing, record:
Date
Assessor
Testing side
Skinfold sites used
Caliper type
Recent exercise if relevant
Any reason the result may not compare directly with previous sessions
Choose one side of the body and use it consistently.
Many anthropometry protocols use the right side of the body as standard. If another side is used, record it clearly in Measurz and repeat the same side at retest.
Do not compare right-side and left-side results unless your protocol specifically requires bilateral measurement.
The Durnin and Womersley 4-site method uses:
Biceps skinfold
Measured on the front of the upper arm over the biceps region.
Triceps skinfold
Measured on the back of the upper arm over the triceps region.
Subscapular skinfold
Measured below the lower angle of the shoulder blade.
Suprailiac skinfold
Measured above the iliac crest in the side/hip region.
The exact landmarking method should follow your chosen protocol and be repeated consistently.
Use a skin-safe marker to identify each site.
Good landmarking is important because even small site differences can affect the result.
If using a standardised anthropometry approach, locate and mark the site before taking the fold. Avoid guessing the site visually without confirming the landmark.
Use the thumb and index finger to gently lift a fold of skin and subcutaneous tissue.
The fold should include skin and underlying subcutaneous tissue, not muscle.
Hold the fold firmly but comfortably. The fold should be lifted away from the underlying muscle before the calipers are applied.
Place the caliper jaws about 1 cm below the fingers holding the fold, depending on the site and protocol.
The calipers should be applied at the correct angle for the site.
Keep holding the fold while the caliper reading is taken.
Allow the calipers to settle according to your chosen protocol, then record the reading in millimetres.
Avoid leaving the calipers on too long, as the tissue may compress and reduce the reading.
Take repeated measurements at each site.
A practical approach is:
Measure each site once
Move through all four sites
Repeat each site again
Take a third measurement if values are not close
Record the average or protocol-defined value
Avoid taking repeated measurements on the same site too quickly, as compression can affect the result.
Add the four skinfold values together:
Biceps
Triceps
Subscapular
Suprailiac
The result is the sum of 4 skinfolds, recorded in millimetres.
This sum is often the clearest practical value for progress tracking.
Record each site and the sum of 4 skinfolds in Measurz.
Useful notes include:
Testing side
Assessor
Calipers used
Site landmarking method
Number of trials
Any sites that were difficult to measure
Recent exercise, hydration or other relevant factors
The main scores are:
Biceps skinfold in millimetres
Triceps skinfold in millimetres
Subscapular skinfold in millimetres
Suprailiac skinfold in millimetres
Sum of 4 skinfolds in millimetres
Optional estimated body fat percentage if using a validated equation
A lower sum of skinfolds generally reflects lower measured subcutaneous fat thickness across the four sites. A higher sum reflects higher measured subcutaneous fat thickness across the four sites.
Interpretation should consider:
Client baseline
Change over time
Measurement error
Assessor consistency
Caliper quality
Training history
Nutrition context if relevant
Weight change
Girth changes
Strength and performance results
Client goals
Population suitability of any equation used
The sum of skinfolds is often more useful for tracking than a single site. A body fat percentage estimate may be helpful in some settings, but it should be interpreted cautiously because equations do not fit every person equally well.
Skin Folds 4 Sites does not have one simple universal “normal” value. The classic Durnin and Womersley method uses the biceps, triceps, subscapular and suprailiac sites to estimate body density and body fat percentage. More recent peer-reviewed work has also provided adult centile curves for larger skinfold sums, such as the sum of eight skinfolds, but this is not the same as the 4-site method. For Measurz, the most useful comparison is usually the person’s own baseline, each individual site, the sum of 4 skinfolds, body weight, girths and performance results.
Skinfold testing can be useful, but it depends heavily on assessor skill.
Reliability improves when:
The same assessor performs the test
The same calipers are used
The same testing side is used
The same sites are marked carefully
The same protocol is followed
Multiple measurements are taken
Technical error is monitored
The client is tested under similar conditions
Results are recorded clearly in Measurz
Validity depends on the purpose. Skinfolds are valid for measuring skinfold thickness at specific sites when performed correctly. They can estimate body fat percentage when used with appropriate equations, but the estimate is not perfect and may be less accurate in some populations.
Common errors include:
Measuring the wrong site
Not marking the site
Using inconsistent landmarks
Pinching muscle instead of skin and subcutaneous tissue
Reading the calipers too early or too late
Taking repeated measurements too quickly at the same site
Using poor-quality calipers
Using different assessors between sessions
Comparing results from different equations
Treating estimated body fat percentage as exact
Limitations include:
Skinfolds require training and practice
Results depend on assessor technique
Some sites may be uncomfortable or sensitive
Equations may not suit every client
Skinfolds do not measure visceral fat
Skinfolds do not directly measure muscle mass
Body fat percentage estimates are not exact
A single test should not be used to judge health or performance
4-site skinfolds may be useful for:
Body composition tracking
Fitness and performance profiling
Monitoring changes during training blocks
Supporting weight-change interpretation
Comparing skinfold change with girth change
Comparing skinfold change with strength and endurance changes
Client education
Progress reporting in Measurz
Long-term body measurement tracking
For example, if body weight stays the same but the sum of skinfolds decreases and strength improves, this may suggest a positive change in body composition and performance profile. If weight decreases but skinfolds do not change, the professional should consider other factors such as hydration, muscle mass or measurement conditions.
When recording Skin Folds (4 Sites) in Measurz, include:
Client name
Test date
Testing side
Biceps skinfold
Triceps skinfold
Subscapular skinfold
Suprailiac skinfold
Sum of 4 skinfolds
Caliper type
Assessor
Number of trials
Any site-specific notes
Any reason the test may not compare directly with previous sessions
For best results, use the same protocol, same side, same calipers and same assessor whenever possible.
Measurz can help organise skinfold values alongside weight, BMI, girths, strength, endurance and performance data so body measurement changes can be interpreted more clearly.
The common 4-site Durnin and Womersley method uses biceps, triceps, subscapular and suprailiac skinfolds.
Skinfolds are usually recorded in millimetres.
It is the total of the four measured skinfold values.
No. Skinfold testing estimates subcutaneous fat thickness and can estimate body fat percentage if an appropriate equation is used. It is not exact.
Yes, where possible. Skinfold testing is technique-sensitive, so using the same trained assessor improves consistency.
Yes, skinfolds are commonly used in sport settings, but interpretation should focus on trends and context rather than a single “ideal” number.
No. Skinfold values vary widely between people and populations.
It may feel like a firm pinch, but it should be performed professionally and respectfully.
Skin Folds (4 Sites) measures skinfold thickness at biceps, triceps, subscapular and suprailiac sites.
The sum of 4 skinfolds is often useful for tracking change over time.
Skinfold testing depends heavily on accurate landmarking and assessor technique.
There are no simple universal skinfold norms.
Skinfolds estimate subcutaneous fat thickness, not total health, fitness or performance.
The result should be interpreted alongside other Measurz assessment findings.
Durnin, J. V. G. A., & Womersley, J. (1974). Body fat assessed from total body density and its estimation from skinfold thickness: Measurements on 481 men and women aged from 16 to 72 years. British Journal of Nutrition, 32(1), 77–97. https://doi.org/10.1079/BJN19740060
Lohman, T. G., Roche, A. F., & Martorell, R. (Eds.). (1988). Anthropometric standardization reference manual. Human Kinetics.
Marfell-Jones, M., Stewart, A., & de Ridder, H. (2012). International standards for anthropometric assessment. International Society for the Advancement of Kinanthropometry.
Norton, K., & Olds, T. (Eds.). (1996). Anthropometrica: A textbook of body measurement for sports and health courses. UNSW Press.
Siri, W. E. (1961). Body composition from fluid spaces and density: Analysis of methods. In J. Brožek & A. Henschel (Eds.), Techniques for measuring body composition (pp. 223–244). National Academy of Sciences.
Durnin, J. V. G. A., & Womersley, J. (1974). Body fat assessed from total body density and its estimation from skinfold thickness: Measurements on 481 men and women aged from 16 to 72 years. British Journal of Nutrition, 32(1), 77–97. https://doi.org/10.1079/BJN19740060
Campa, F., Coratella, G., Petri, C., Spataro, F., Charrier, D., Cerullo, G., Baroncini, G., Faraone, E., Marinelli, G. P. A., Serafini, S., Vaccaro, S., Pincella, M., Izzicupo, P., & Paoli, A. (2025). From fat to facts: Anthropometric references and centile curves for sum of skinfolds and waist-to-hip ratio in 2,507 adults. PLOS ONE, 20(6), e0326111. https://doi.org/10.1371/journal.pone.0326111
