The Jackson-Pollock equations are scientifically validated formulas that calculate body density and percent body fat from skinfold measurements, developed through extensive research by Dr. Andrew Jackson and M. L. Pollock. These equations are widely used in athletic performance assessment and sports science.

How to Use the Jackson-Pollock Calculator

Follow these simple steps to calculate your body composition:

  1. Select Your Gender and Age - Choose male or female and enter your age in years. The equations differ between genders and age affects body composition calculations.
  2. Choose Measurement Method - Select 3-site (quick assessment), 4-site (standard), or 7-site (most comprehensive) based on your available measurements.
  3. Toggle Units if Needed - Use the metric/imperial toggle to switch between millimeters and inches for your convenience.
  4. Enter Skinfold Measurements - Input your skinfold thickness in your preferred units for each required site. Measurements should be taken on the right side of the body.
  5. Calculate Results - Click calculate to get your body density and body fat percentage instantly.

Pro Tip: For most accurate results, have a trained professional take your skinfold measurements using calibrated calipers. Take measurements at the same time of day, preferably morning before training.

Understanding the Jackson-Pollock Equations

Once body density is calculated using the equations below, the level of percent bodyfat (%BF) can be determined using the Siri Equation. The different measurement protocols offer varying levels of precision and practicality for athletic assessment.

Body Fat Percentage Equations

Males - 4-Site Skinfold Equation

% Body Fat = (0.29288 x sum of skinfolds) – (0.0005 x square of the sum of skinfolds) + (0.15845 x age) – 5.76377, where the skinfold sites (measured in mm) are abdominal, triceps, thigh and suprailiac.

Females - 4-Site Skinfold Equation

% Body Fat = (0.29669 x sum of skinfolds) – (0.00043 x square of the sum of skinfolds) + (0.02963 x age) + 1.4072, where the skinfold sites (measured in mm) are abdominal, triceps, thigh and suprailiac.

Females - 3-Site Skinfold Equation

% Body Fat = (0.41563 x sum of skinfolds) – (0.00112 x square of the sum of skinfolds) + (0.03661 x age) + 4.03653, where the skinfold sites (measured in mm) are abdominal, triceps and suprailiac.

Body Density Equations

Males - Equation Including Girth Measurements

Body Density = 1.0990750 - 0.0008209 (X₂) + 0.0000026 (X₂)² - 0.0002017 (X₃) - 0.005675 (X₄) + 0.018586 (X₅). Where X₂ = sum of the chest, abdomen and thigh skinfolds in mm, X₃ = age in years, X₄ = waist circumference in m, and X₅ = forearm circumference in m.

Males - 3-Site Skinfold Equation

Body Density = 1.1125025 - (0.0013125 x sum of chest, triceps and subscapular skinfolds in mm) + (0.0000055 x square of the sum of chest, triceps and subscapular) - (0.000244 x age)
reference: Jackson, A.S. & Pollock, M.L. (1985)

Males - 3-Site Skinfold Equation (Alternative)

Body Density = 1.10938 - (0.0008267 x sum of chest, abdomen and thigh skinfolds in mm) + (0.0000016 x square of the sum of chest, abdomen and thigh) - (0.0002574 x age)
(reference: Jackson, A.S. & Pollock, M.L. (1978), based on a sample aged 18-61)

Males - 7-Site Skinfold Equation

Body Density = 1.112 - (0.00043499 x sum of skinfolds) + (0.00000055 x square of the sum of skinfold sites) - (0.00028826 x age), where the skinfold sites (measured in mm) are: Chest, Axilla, Tricep, Subscapular, Abdominal, Suprailiac and Thigh.
(reference: Jackson, A.S. & Pollock, M.L. (1978), based on a sample aged 18-61)

Females - Equation Including Girth Measurements

Body Density = 1.1470292 - 0.0009376 (X₃) + 0.0000030 (X₃)² - 0.0001156 (X₄) - 0.0005839 (X₅), Where: X₃ = sum of triceps, thigh and suprailiac skinfolds, in mm, X₄ = age in years and X₅ = gluteal circumference in cm.

Females - 3-Site Skinfold Equation

Body Density = 1.0994921 - (0.0009929 x sum of triceps, thigh and suprailiac skinfolds) + (0.0000023 x square of the sum of triceps, thigh and suprailiac skinfolds) - (0.0001392 x age)
(reference: Jackson, et al. (1980), based on a sample aged 18-55)

Females - 7-Site Skinfold Equation

Body Density = 1.097 - (0.00046971 x sum of skinfolds) + (0.00000056 x square of the sum of skinfold sites) - (0.00012828 x age), where the skinfold sites (measured in mm) are: Chest Axilla, Triceps, Subscapular, Abdominal, Suprailiac and Thigh.
(reference: Jackson, et al. (1980), based on a sample aged 18-55)

Body Composition for Athletes and Sports

Sport-Specific Body Fat Standards

Endurance Athletes

Marathon/Distance Running: Males 5-10%, Females 10-16%
Elite marathoners typically maintain lower body fat percentages to optimize power-to-weight ratio. Lower body fat improves running economy and thermoregulation during long events.

Cycling: Males 5-11%, Females 12-18%
Professional cyclists balance low body fat with maintaining power output. Climbers tend toward the lower range, while sprinters may carry slightly more muscle mass.

Triathlon: Males 5-12%, Females 10-18%
Triathletes require slightly higher body fat than single-sport endurance athletes for buoyancy in swimming and energy reserves for multi-discipline events.

Using Results for Athletic Training

Based on your calculated body composition, adjust training and nutrition strategies:

Below Target Range

May indicate insufficient energy availability. Consider increasing caloric intake, particularly carbohydrates for endurance athletes. Monitor performance metrics and recovery.

At Target Range

Maintain current nutrition and training balance. Focus on performance improvements and skill development. Monitor body composition monthly during training phases.

Above Target Range

Create modest caloric deficit (300-500 kcal/day). Emphasize strength training to preserve muscle mass. Gradual reduction recommended during off-season.

Measurement Technique and Accuracy

The accuracy of the Jackson-Pollock method depends heavily on proper measurement technique. According to research by Robert Wood, MSc Sports Science, founder of TopEndSports, consistent technique is more important than the specific equation used.

"When measuring skinfolds for body composition assessment, consistency in technique and measurement sites is paramount. A trained assessor using proper anatomical landmarks can achieve test-retest reliability within 1-2mm, which translates to body fat percentage accuracy of ±2% for athletes."
--- Robert J. Wood, PhD, Founder of TopEndSports

Key Measurement Guidelines

  • Timing: Measure at the same time of day, preferably morning before training when hydration is consistent
  • Side: All measurements taken on the right side of the body
  • Technique: Pinch fold perpendicular to natural skin lines, measure 4 seconds after pinch
  • Repetition: Take 2-3 measurements at each site, use average if within 2mm
  • Equipment: Use calibrated calipers (Harpenden, Lange, or similar quality)

⚠️ Important Note: Body composition is just one metric of athletic performance. Focus on performance indicators specific to your sport, energy levels, and overall health rather than pursuing arbitrary body fat targets.

Frequently Asked Questions

What is the difference between 3-site and 7-site Jackson-Pollock measurements?

The 3-site method uses fewer measurement points for quicker assessment, while the 7-site method provides more comprehensive data. The 7-site method is typically 1-2% more accurate but requires more time and expertise to perform correctly.

How often should athletes measure body composition using skinfolds?

Athletes should measure body composition every 4-8 weeks during training phases. More frequent measurements aren't recommended as normal fluctuations in hydration and glycogen can affect results. Consistency in measurement conditions is key for tracking trends.

Can I use the Jackson-Pollock calculator if I'm not an athlete?

Yes, the Jackson-Pollock equations are validated for both athletes and general population aged 18-61. However, interpretation of results should consider your activity level and fitness goals. Non-athletes typically have higher healthy body fat ranges than competitive athletes.

Why do male and female formulas differ in the Jackson-Pollock method?

Men and women have different body fat distribution patterns due to biological differences. Women naturally carry more essential fat (12% vs 3% in men) for hormonal and reproductive functions. The gender-specific equations account for these physiological differences.

What factors can affect the accuracy of skinfold measurements?

Hydration status, recent exercise, measurement technique, caliper quality, and skin compressibility all affect accuracy. For best results, measure when normally hydrated, avoid testing immediately after exercise, and have the same trained professional take measurements each time.

References

  1. Jackson, A. S., & Pollock, M. L. (1978). "Generalized equations for predicting body density of men." British Journal of Nutrition, 40, 497-504.
  2. Jackson, A. S., Pollock, M. L., & Ward, A. (1980). "Generalized equations for predicting body density of women." Medicine and Science in Sports and Exercise, 12, 175-182.
  3. Jackson A S, Pollock, M (1985). "Practical assessment of body composition." Physician Sport Med. 13: 76-90.
  4. Siri, W.E. (1956). "The gross composition of the body." Advances in Biological and Medical Physics, 4, 239-280.
  5. American College of Sports Medicine. (2021). "ACSM's Guidelines for Exercise Testing and Prescription." 11th Edition.
  6. Wood, R. J. (2008). "Reliability of skinfold measurements in sports science." TopEndSports Research Papers.
  7. National Strength and Conditioning Association. (2020). "Body Composition Assessment in Athletes." NSCA Position Stand.
  8. McArdle, W. D., Katch, F. I., & Katch, V. L. (2015). "Exercise Physiology: Nutrition, Energy, and Human Performance." 8th Edition.

Related Pages

Body Density Information

Learn more about body density measurement methods and calculations.

Body Density Guide →

Skinfold Testing Protocols

Detailed instructions for taking accurate skinfold measurements.

Measurement Techniques →

Body Fat Norms

Reference values for body fat percentages in athletes and general population.

Body Fat Standards →