Skinfold Thickness Calculator

What Is the Skinfold Thickness Calculator

This calculator estimates body density and body fat percentage from caliper-based skinfold measurements, age, and sex. It supports Jackson-Pollock 3-site and 7-site methods for practical fitness tracking.

How to Use

1. Choose sex and method (3-site or 7-site).
2. Enter age and required skinfold sites in millimeters.
3. Run calculation to get body fat, body density, skinfold sum, and category range.
4. Record results under consistent conditions for better trend comparison.

Formula Notes

• Both methods first compute skinfold sum S, then estimate body density BD by age and sex.
• 3-site (male): BD = 1.10938 - 0.0008267*S + 0.0000016*S² - 0.0002574*age
• 3-site (female): BD = 1.0994921 - 0.0009929*S + 0.0000023*S² - 0.0001392*age
• 7-site (male): BD = 1.112 - 0.00043499*S + 0.00000055*S² - 0.00028826*age
• 7-site (female): BD = 1.097 - 0.00046971*S + 0.00000056*S² - 0.00012828*age
• Body fat conversion: Body Fat (%) = 495 / BD - 450

Use Cases

• Weekly fat-loss review to evaluate training and nutrition adjustments.
• Body composition tracking during hypertrophy or recomposition phases.
• Before/after fitness test review to plan the next training cycle.

Notes

• Measurement noise often comes from site location and pinch consistency; average repeated readings.
• Results from different methods are useful for trends, but not ideal for direct cross-method comparison.
• This tool is for health and training reference and does not replace medical diagnosis.