Anthropometrics Measurement: Skin Folds 4 Sites

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.

What Is Skin Folds (4 Sites)?

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.

Why It Is Used

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.

What It Measures

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.

Equipment Required

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.

How to Measure Skin Folds (4 Sites)

1. Prepare the client

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

2. Use the same testing side

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.

3. Identify the four sites

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.

4. Mark the measurement sites

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.

5. Lift the skinfold

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.

6. Apply the calipers

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.

7. Read the measurement

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.

8. Repeat each site

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.

9. Calculate the sum of 4 skinfolds

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.

10. Save the result in Measurz

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

Scoring and Interpretation

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.

Normative Data, Benchmarks or Reference Values

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.

Reliability and Validity

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 and Limitations

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

Practical Applications

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.

How to Record This in Measurz

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.

FAQs

What are the four skinfold sites?

The common 4-site Durnin and Womersley method uses biceps, triceps, subscapular and suprailiac skinfolds.

What unit is used for skinfolds?

Skinfolds are usually recorded in millimetres.

What is the sum of 4 skinfolds?

It is the total of the four measured skinfold values.

Does skinfold testing measure body fat exactly?

No. Skinfold testing estimates subcutaneous fat thickness and can estimate body fat percentage if an appropriate equation is used. It is not exact.

Should I use the same assessor each time?

Yes, where possible. Skinfold testing is technique-sensitive, so using the same trained assessor improves consistency.

Can skinfolds be used for athletes?

Yes, skinfolds are commonly used in sport settings, but interpretation should focus on trends and context rather than a single “ideal” number.

Are there universal skinfold norms?

No. Skinfold values vary widely between people and populations.

Is skinfold testing uncomfortable?

It may feel like a firm pinch, but it should be performed professionally and respectfully.

Key Takeaways

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.

References

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