Before you begin
- Measure on the right side of the body.
- Locate and mark every site before taking readings.
- Grasp the skin and subcutaneous fat with the thumb and index finger, pulling the fold away from the underlying muscle.
- Place the caliper jaws about 1 cm below your fingers and perpendicular to the fold.
- Keep holding the fold and read the caliper after its pressure settles, usually after 2 to 3 seconds.
- Keep the muscle relaxed. Avoid measuring immediately after exercise.
- For three rounds, measure each site once before returning to the first site. Use the median for each site.
Which sites does each protocol use?
| Protocol | Sites |
|---|---|
| Male 3-site | Chest, abdomen, thigh |
| Female 3-site | Triceps, suprailiac, thigh |
| Male 7-site | Chest, midaxillary, triceps, subscapular, abdomen, suprailiac, thigh |
| Female 7-site | Chest, midaxillary, triceps, subscapular, abdomen, suprailiac, thigh |
The seven measurement sites
Chest
Male: Find the anterior axillary crease, the front crease where the upper arm meets the chest. Mark the midpoint of a diagonal line between that crease and the nipple.
Female: Follow the same diagonal line, but mark one-third of the distance from the anterior axillary crease toward the nipple. Do not include breast tissue.
Grasp a diagonal fold running downward and inward toward the nipple.
Triceps
Find the acromion at the top and outer edge of the shoulder and the olecranon at the bony tip of the elbow. Mark their midpoint on the posterior midline, the center of the back of the upper arm.
Let the arm hang loose and take a vertical fold.
Subscapular
Find the inferior angle, the lowest tip of the shoulder blade. Mark a point 1 to 2 cm below it.
Take a diagonal fold following the natural crease, downward and outward at about 45 degrees. An assistant is recommended.
Midaxillary
Find the midaxillary line, an imaginary vertical line descending from the center of the armpit. Find the xiphoid process at the lower tip of the sternum and trace its level horizontally to the midaxillary line.
Raise the right arm enough to expose the mark and take a vertical fold.
Abdomen
Find the umbilicus, the belly button. Mark a point 2 cm directly to its right.
Relax the abdominal muscles, breathe normally, and take a vertical fold without drawing in the abdomen.
Suprailiac
Follow the anterior axillary line, descending from the front crease of the armpit, to the superior border of the iliac crest. Mark the point immediately above the crest.
Take a diagonal fold that follows the crest downward and forward. Do not substitute a midaxillary, iliac crest, or supraspinale site from another protocol.
Thigh
Find the inguinal crease where the front of the thigh meets the pelvis and the proximal border at the top of the kneecap. Mark the midpoint along the center of the front of the thigh.
Shift weight to the opposite leg and take a vertical fold while the measured thigh remains relaxed.
Final anatomical illustrations are in production. The Caliper Cal app pairs these written instructions with site-specific guidance artwork.
How to interpret the result
Caliper Cal estimates body density with sex-specific Jackson-Pollock regression equations and converts density to an estimated body-fat percentage with the Siri equation. The result is not a direct measurement of total body fat.
The original male study included adults ages 18 to 61. The original female study included adults ages 18 to 55 and advised extra care for women over 40. Results can be less accurate when a person differs from the original research samples in age, body-fat level, ethnicity, fat distribution, athletic population, or recent major weight loss.
Use the same caliper, measurer, protocol, locations, and general conditions each time. A consistent series can be more informative than any one estimate.
Medical disclaimer
Caliper Cal is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. Results are estimates for general fitness and informational purposes. Consult a qualified healthcare professional for medical advice and before making decisions that could affect your health.