Skinfold Sites
This "handy" site is located on the posterior midline of the upper arm, halfway between the acromion and olecranon processes.
What are the triceps?
This handheld instrument, featuring two spring-loaded jaws, is the primary tool used to measure the thickness of a skinfold in millimeters.
What is a caliper?
Before calculating body fat percentage, most standardized formulas require you to find this value by adding the measurements from all selected sites.
What is the sum of skinfolds?
Unlike body mass index (BMI), which only uses height and weight, skinfold testing allows a practitioner to distinguish between fat mass and this, which includes muscle, bone, and organs.
What is fat-free mass or lean body mass?
This is the single greatest source of error in skinfold testing, often caused by poor technique or a lack of experience by the person performing the pinch.
What is technician error? Or inter-tester reliability?
A vertical fold at this site is taken on the anterior midline, midway between the proximal border of the patella and inguinal fold.
What is the thigh?
These two specific brands; one starting with 'H' and the other with 'L'- are the research-grade calipers most frequently cited in clinical studies for their consistent jaw tension.
What are Harpenden and Lange calipers?
Many generalized equations, such as Jackson-Pollock, do not directly calculate fat percentage but first solve for this variable, representing the mass per unit volume of the body.
What is body density?
Skinfold testing is based on the physiological principle that approximately 50% of total body fat is located in this specific layer, situated directly beneath the dermis.
What is subcutaneous fat?
The primary limitation of this method is that it only measures fat located directly under the skin, completely ignoring this "hidden" fat stored around internal organs.
What is visceral fat?
What is the pectoral (chest) site?
To ensure accuracy over time, this specific procedure must be performed using a calibration block or a specialized step wedge to verify the calipers are exerting the required 10 g/mm^2 pf pressure.
These two common equations- one named for Siri and one for Brozek- are used to convert body density into a final body fat percentage?
What are the Siri and Brozek equations?
In clinical reviews, skinfold testing is often preferred over "Gold Standard" methods like hydrostatic weighing or DXA because of these two practical factors.
What are portability and cost-effectiveness? Or ease of use in the field?
Skinfold measurements become significantly less accurate and physically difficult to perform on individuals with this classification, defined as a BMI or 30 or higher.
What is obesity? Or class 1 obesity?
This measurement is taken using a diagonal fold in line with the natural angle of the iliac crest, at the anterior axillary line immediately superior to the hip bone.
What is the suprailiac?
Before pinching, technicians use this tool to ensure they are at the exact midpoint of a limb, preventing "measurement drift" between sessions.
What is a flexible (non-elastic) Gulick tape measure?
In addition to skinfold thickness, the generalized Jackson-Pollock equations require this specific demographic variable to account for the gradual shift of subcutaneous fat to internal depots over time.
What is age?
In 2026, elite sport scientists emphasize that the most valuable use of skinfold data is not the single estimated "fat percentage" but the monitoring of this over a competitive season.
What is tracking changes over time? Or longitudinal monitoring?
Accuracy can be skewed by this physiological factor; if a subject has high levels of edema or has just finished a dehydrating workout, the compressibility of the skin changes.
What is hydration status? Or fluid retention?
Located 1-2 cm below the inferior angle of the scapula, this site requires a diagonal fold at a 45-degree angle.
What is the subscapular?
According to standardized ISAK and ACSM protocols, all measurements must be taken using the tool on this specific side of the subject's body to maintain consistency.
What is the right side?
Advanced skinfold calculations use this type of mathematical model (often called a "quadratic) because the relationship between skinfold thickness and body density is not a straight line, but rather a curve.
What is a non-linear (or curvilinear/quadratic) equation?
Unlike bioelectrical impedance (BIA), skinfold measurements allow practitioners to identify these specific patterns, which can help assess health risks like android versus gynoid fat storage.
What is regional fat distribution? Or adipose tissue patterning?
A major mathematical limitation is the assumption that the density of this compartment-which includes muscle and bone- is the same for everyone, regardless of age, ethnicity, or fitness level.
What is fat-free mass density?