Body Fat Percent Jackson Pollock Calculator
Free Body fat percent jackson pollock Calculator for overall fitness. Enter your stats to get performance metrics and improvement targets.
Formula
BD = 1.10938 - 0.0008267(S) + 0.0000016(S^2) - 0.0002574(A)
Jackson-Pollock 3-site equation for men where BD = body density, S = sum of chest + abdominal + thigh skinfolds in mm, A = age. Body fat percentage is then calculated using the Siri equation: BF% = (495 / BD) - 450.
Worked Examples
Example 1: Male 3-Site Skinfold Assessment
Problem: A 25-year-old male: chest skinfold 10mm, abdominal 18mm, thigh 14mm. Weight 78 kg, height 180 cm.
Solution: Sum of skinfolds = 10 + 18 + 14 = 42 mm\nBody density = 1.10938 - 0.0008267(42) + 0.0000016(42^2) - 0.0002574(25)\nBD = 1.10938 - 0.03472 + 0.00282 - 0.00644 = 1.07104\nBF% (Siri) = (495 / 1.07104) - 450 = 12.2%\nFat mass = 78 x 0.122 = 9.5 kg\nLean mass = 78 - 9.5 = 68.5 kg
Result: Body Fat: 12.2% (Athletic) | Fat Mass: 9.5 kg | Lean Mass: 68.5 kg
Example 2: Female 3-Site Skinfold Assessment
Problem: A 32-year-old female: tricep skinfold 16mm, suprailiac 20mm, thigh 22mm. Weight 62 kg, height 165 cm.
Solution: Sum of skinfolds = 16 + 20 + 22 = 58 mm\nBody density = 1.0994921 - 0.0009929(58) + 0.0000023(58^2) - 0.0001392(32)\nBD = 1.0994921 - 0.05759 + 0.00774 - 0.00446 = 1.04518\nBF% (Siri) = (495 / 1.04518) - 450 = 23.6%\nFat mass = 62 x 0.236 = 14.6 kg\nLean mass = 62 - 14.6 = 47.4 kg
Result: Body Fat: 23.6% (Fitness) | Fat Mass: 14.6 kg | Lean Mass: 47.4 kg
Frequently Asked Questions
What is the Jackson-Pollock skinfold method for measuring body fat?
The Jackson-Pollock method is a widely validated skinfold-based body composition assessment developed by researchers Andrew Jackson and Michael Pollock in 1978. It uses skinfold caliper measurements at specific anatomical sites to estimate total body density, which is then converted to body fat percentage using the Siri or Brozek equation. The most common version is the 3-site protocol, which measures different locations depending on gender. For men, the chest, abdominal, and thigh skinfolds are measured. For women, the tricep, suprailiac, and thigh skinfolds are used. The method remains one of the most practical and accessible body composition assessment techniques available outside of laboratory settings.
How accurate is the Jackson-Pollock 3-site formula compared to other methods?
The Jackson-Pollock 3-site formula has been validated against underwater weighing (hydrostatic densitometry) and typically shows a standard error of estimate of 3.5 to 4.0 percent body fat. This means that if the formula estimates 15 percent body fat, the true value likely falls between 11 and 19 percent. This accuracy is comparable to bioelectrical impedance analysis and superior to BMI-based estimates. The 7-site Jackson-Pollock formula offers slightly better accuracy with a standard error of about 3.0 percent. DEXA scans achieve approximately 1.5 to 2.5 percent accuracy, while underwater weighing and air displacement plethysmography achieve 2 to 3 percent. For tracking changes over time, consistent skinfold measurement is highly reliable.
What body fat percentage ranges are considered healthy for men and women?
Body fat ranges differ significantly between genders because women carry essential fat in breasts, hips, and reproductive organs. For men, essential fat (minimum for health) is 2 to 5 percent. Athletic range is 6 to 13 percent. Fitness range is 14 to 17 percent. Average is 18 to 24 percent, and above 25 percent is considered obese. For women, essential fat is 10 to 13 percent. Athletic range is 14 to 20 percent. Fitness range is 21 to 24 percent. Average is 25 to 31 percent, and above 32 percent is considered obese. Extremely low body fat in either gender causes hormonal disruption, immune suppression, and loss of bone density. Most health professionals recommend staying above 6 percent for men and 14 percent for women.
Why does the calculator use body density as an intermediate step?
The Jackson-Pollock equations were developed by correlating skinfold measurements with body density measured via hydrostatic (underwater) weighing. Body density is the ratio of body mass to body volume. Since fat tissue has a lower density (approximately 0.900 g/mL) than lean tissue (approximately 1.100 g/mL), total body density inversely correlates with body fat percentage. The Siri equation converts density to body fat: BF% = (495/density) - 450. The Brozek equation offers an alternative: BF% = (457/density) - 414.2. Both assume consistent densities for fat and lean tissue, which is generally valid but can be affected by hydration status, bone mineral density, and ethnicity. These conversion equations are well-established in exercise physiology.
How does age affect body fat distribution and skinfold accuracy?
Age significantly affects both the amount and distribution of body fat. As people age, fat tends to redistribute from subcutaneous sites (under the skin, where skinfolds measure) to visceral sites (around internal organs). This shift means that skinfold measurements may underestimate true body fat in older individuals because a larger proportion of their total fat is stored internally rather than subcutaneously. The Jackson-Pollock equations include age as a variable to partially account for this phenomenon, but the correction is not perfect. After age 50, the standard error of skinfold-based estimates increases by approximately 1 to 2 percent. For older adults, combining skinfold measurements with waist circumference provides a more complete picture of body composition.
What is the difference between 3-site and 7-site Jackson-Pollock protocols?
The 3-site protocol measures chest, abdominal, and thigh for men, or tricep, suprailiac, and thigh for women. It is faster and simpler but captures fewer measurement points. The 7-site protocol adds subscapular, midaxillary, chest, and tricep measurements for men, or adds chest, midaxillary, subscapular, and abdominal measurements for women. More measurement sites improve accuracy by better sampling the body fat distribution pattern, reducing the standard error from approximately 3.9 percent to 3.0 percent. The 7-site protocol takes about 5 to 10 minutes longer and requires more anatomical knowledge. For general fitness tracking, the 3-site protocol provides sufficient accuracy. For research or clinical applications, the 7-site protocol is preferred.