Log your skinfolds. Watch the trend. Ignore the noise. Your data stays in your browser.
This tracker uses the Jackson-Pollock 3-site and 7-site protocols to estimate body fat percentage from skinfold thickness measurements. You enter measurements in millimeters for each site, select your protocol (3-site for quick checks, 7-site for more accuracy), and the tool calculates body density using the Siri equation, then converts to body fat percentage. The 3-site protocol uses chest, abdomen, and thigh for men; triceps, suprailiac, and thigh for women. The 7-site adds midaxillary and subscapular for a more complete picture. All entries are saved locally with timestamps so you can track trends over weeks and months.
Tip: Self-measurement error is typically ±8%. For best results, have a trained partner measure for you, or practice the pinching technique until your readings stabilize within 1-2mm across three attempts.
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⚠️ Technician Error Warning: Self-measurement error is typically ±8%. A skilled technician achieves ±3-5%. Track trends, not absolutes.
Convert your skinfolds to body fat percentage instantly.
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