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This calculator uses the Jackson-Pollock 3-site skinfold method (chest, abdomen, and thigh for men; triceps, suprailiac, and thigh for women) to estimate body density, then converts that to body fat percentage using the Siri equation. This is a standard, published fitness-assessment method requiring skinfold calipers and proper technique — it is a fitness estimate, not a medical diagnosis. Consult a doctor or qualified professional for an actual body composition assessment.
How it works
Enter your sex, age, and the three relevant skinfold measurements in millimeters. The tool sums the skinfolds, applies the sex-specific Jackson-Pollock body density equation, then converts density to body fat percentage using the Siri formula: BF% = (495 / density) - 450.
- Enter sex.
- Enter age (years).
- Enter chest skinfold (mm).
- Enter abdomen skinfold (mm).
- Enter triceps skinfold (mm).
- Enter suprailiac skinfold (mm).
- Enter thigh skinfold (mm).
- Click Calculate to see your results.
Examples
A 30-year-old man with a 50mm total (3-site)
Body density and the Siri equation together typically yield a body fat estimate in the high-teens to low-20s percent range for a total like this — exact results depend on age.
Who should use it
- Tracking body composition changes over a training program.
- Quick, low-cost body fat estimate at a gym or clinic.
Industry applications
- Fitness assessment and personal training
- Sports science research
Advantages
- Inexpensive — requires only skinfold calipers.
- Based on peer-reviewed, widely used published equations.
Limitations
- Sensitive to measurement technique and taker experience.
- Less precise than lab methods like DEXA or hydrostatic weighing.
Common mistakes to avoid
- Inconsistent caliper technique (pinch depth, site location) between measurements.
- Taking a single reading per site instead of averaging 2-3 readings for accuracy.
Best practices
- Take each skinfold measurement 2-3 times and average them, always pinching at the same marked site.
Tips
- Have the same person take your measurements each time using the same calipers for the most consistent tracking.