Sum of Skinfolds Calculator

How it is calculated

The tool adds the caliper readings you enter: sum = s1 + s2 + s3 + s4 + s5 + s6 + s7, each reading being the skinfold thickness in millimetres at one body site. Up to seven sites can be used, and any field left empty is simply skipped, so you can enter three sites, four sites or all seven. The only validation is that a reading cannot be negative; a negative number returns no result. If all fields are empty there is also no result. The total is shown in millimetres with two decimals. The tool does not estimate body-fat percentage or body density: it gives the raw total only, which you can compare over time or enter into a formula you have chosen. Make sure the same sites and the same protocol are used every time.

Common mistakes

• Mixing different site sets between sessions. A 4-site total cannot be compared with a 7-site total, because the sum depends on how many places were measured.
• Typing an average instead of each reading. Take the reading at each site (often a few repeats, then one value) and enter one number per site, not the mean of all sites.
• Entering the pinch width in centimetres or the caliper reading in inches. The fields are in millimetres, so 1.2 cm is 12.
• Treating the sum as body-fat percentage. It is a total thickness in millimetres; turning it into a percentage needs a separate equation that also uses age and sex.
• Leaving a measured site as 0 when it was not measured. Zero adds nothing, but it can be mistaken later for a real reading, so clear unused fields instead.