Calculate Body Fat % (Jackson-Pollock 7-Site)
Enter your measurements in millimeters (mm). This calculator estimates body density and body fat percentage using the 7-site skinfold method.
What is the 7-site skinfold method?
The 7-site skinfold method is a field-friendly way to estimate body fat percentage. You measure skinfold thickness at seven standardized locations, add those values, and apply a validated equation. This method is widely used by coaches, trainers, and health professionals because it is inexpensive, practical, and repeatable when technique is good.
The 7 skinfold sites
- Chest / pectoral – diagonal fold between the armpit and nipple line.
- Midaxillary – vertical fold on the mid-axillary line (side of torso), level with the xiphoid process.
- Triceps – vertical fold at the back of the upper arm, midway between shoulder and elbow.
- Subscapular – diagonal fold just below the lower angle of the shoulder blade.
- Abdomen – vertical fold about 2 cm to the side of the navel.
- Suprailiac – diagonal fold just above the iliac crest near the front of the hip.
- Thigh – vertical fold on the front of the thigh, midway between hip and knee.
How this calculator works
This page uses the Jackson-Pollock 7-site equations to estimate body density, then converts that to body fat percentage with the Siri equation:
- Body Fat % = (495 / Body Density) - 450
Equations differ slightly by sex and include age to improve estimate quality. If you enter your body weight, the calculator also estimates fat mass and lean body mass.
How to measure for best accuracy
1) Use proper tools
A quality skinfold caliper gives better consistency than low-tension plastic models. Try to use the same caliper each time you test.
2) Standardize timing
Hydration, training, and inflammation can affect readings. Measure under similar conditions each time (for example, morning, before training).
3) Take repeated readings
At each site, take 2-3 measurements and use the average. If one reading is very different, take another.
4) Track trends, not single-day perfection
Even with excellent technique, skinfold testing has normal error. The biggest value is seeing change over weeks and months.
Body fat categories (general reference)
These broad categories are included in the calculator output:
- Men: Essential (2-5%), Athletes (6-13%), Fitness (14-17%), Average (18-24%), Obese (25%+)
- Women: Essential (10-13%), Athletes (14-20%), Fitness (21-24%), Average (25-31%), Obese (32%+)
These are population-level references, not diagnoses. Athletic goals, age, sport, and health context matter.
Limitations to keep in mind
- Results depend heavily on measurement skill and consistency.
- Very lean or very high-body-fat individuals may see larger error margins.
- Different formulas can produce slightly different estimates.
- This tool is for education and progress tracking, not medical diagnosis.
Bottom line
The 7-site skinfold calculator is one of the best low-cost ways to monitor body composition trends. If you use consistent technique, test under similar conditions, and focus on long-term direction rather than one-off numbers, it can be a powerful progress tool.