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Body Composition • Calipers

Skinfold Calculator

Estimate body fat percentage from three caliper skinfold sites using the Jackson-Pollock method and the Siri equation.

3
Skinfold Sites
Instant
Live Results
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Free

Why Use This Calculator?

  • ✓Jackson-Pollock 3-site formula, separate for men and women.
  • ✓Converts body density to body fat % via the Siri equation.
  • ✓Categorizes results using standard ACE body-fat ranges.

On This Page

Skinfold Calculator Formula Quick Reference Key Terms Explained Where It's Used Worked Examples Tips & Mistakes FAQs

Skinfold Calculator

About Skinfold Calculator

Skinfold testing estimates body fat by pinching a fold of skin and subcutaneous fat at specific sites with calipers. The Jackson-Pollock 3-site method uses three measurements plus age to estimate body density, which is then converted to a body fat percentage using the Siri equation.

Results

Body Fat Percentage
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Category
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Body Density
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Summary

Enter values to see your results.

Skinfold Calculator Formula

Body Density (Men)

BD = 1.10938 − 0.0008267(sum) + 0.0000016(sum)² − 0.0002574(age)

Body Density (Women)

BD = 1.0994921 − 0.0009929(sum) + 0.0000023(sum)² − 0.0001392(age)

Siri Equation

Body Fat % = (495 ÷ Body Density) − 450

Sites Used

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

Quick Reference

CategoryMenWomen
Essential Fat2–5%10–13%
Athletes6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Obese25%+32%+

Measurement Technique

Pinch a vertical or diagonal fold of skin and fat (not muscle), measure with calipers 1cm below your fingers, and average two or three readings per site.

Important Note

Skinfold accuracy depends heavily on tester technique. Trained assessors get more consistent, reliable results than self-measurement.

Key Terms Explained

Skinfold calipers estimate body fat indirectly, by measuring subcutaneous fat thickness at a few representative sites and applying a population-based formula.

📏 Skinfold Site

  • A specific body location pinched and measured with calipers.
  • Sites differ by gender for the 3-site method.
  • Consistency of location matters more than exact millimeter precision.

🧪 Body Density

  • An intermediate value representing mass per unit volume of the body.
  • Higher body density generally means lower body fat.
  • Calculated from the sum of skinfold measurements and age.

🧮 Siri Equation

  • Converts body density into an estimated body fat percentage.
  • One of the most widely used density-to-fat conversions.
  • Assumes standard densities for fat and lean tissue.

✋ Measurement Technique

  • Pinch skin and fat only, not underlying muscle.
  • Measure on the right side of the body by convention.
  • Take 2–3 readings per site and average them.

Where It's Used

🧑‍🏫 Personal Trainer Assessments

A low-cost way for trainers to estimate client body fat.

📈 Body Recomposition Tracking

Track fat loss or gain trends over a training block.

🏫 Team Fitness Testing

Common in school and athletic team fitness assessments.

🥗 Nutrition Coaching

Provides a baseline body-fat estimate to inform calorie targets.

🏆 Physique Competition Prep

Track progress toward a target stage-day body fat level.

🔬 Research & Lab Settings

Used in exercise science studies as a practical field measure.

Worked Examples

Example 1 — Male

Age 30, chest 12mm, abdomen 18mm, thigh 15mm (sum 45) → body fat ≈ 14.6% (Fitness category).

Example 2 — Female

Age 28, triceps 14mm, suprailiac 12mm, thigh 18mm (sum 44) → body fat ≈ 21.8% (Fitness category).

Example 3 — Higher Sum

Male, age 40, sum of sites 75mm → body fat ≈ 24.9% (Average/borderline Obese).

Best Practices & Common Mistakes

✅ Best Practices

  • Always measure on the same side of the body for consistency.
  • Take 2–3 readings per site and use the average.
  • Measure at the same time of day, ideally before exercise.
  • Have the same person measure each time to reduce tester variability.
  • Use skinfold trends over time rather than obsessing over one reading.

❌ Common Mistakes

  • Pinching muscle along with skin and fat.
  • Switching sites or measurer between sessions, which adds noise.
  • Measuring immediately after exercise, when fluid shifts skew readings.
  • Assuming millimeter-level precision from an inexperienced self-measurement.
  • Comparing your result directly to someone measured by a different tester or method.

Frequently Asked Questions

In experienced hands it's typically within about 3-4% of DEXA-measured body fat, but self-measurement error can be considerably larger.
The standard Jackson-Pollock 3-site protocol uses chest, abdomen and thigh for men, and triceps, suprailiac and thigh for women.
Yes, dedicated skinfold calipers apply a standardized, calibrated pinch pressure that a regular ruler or pinch test can't replicate.
The original research found different site combinations correlated best with measured body density for each gender.

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