Heath-Carter Somatotype Calculator

How it is calculated

The tool computes three ratings. Endomorphy: with X = (triceps + subscapular + supraspinale skinfolds, mm) × 170.18 ÷ height, endo = −0.7182 + 0.1451X − 0.00068X² + 0.0000014X³. Mesomorphy: 0.858·humerus + 0.601·femur + 0.188·corrected arm girth + 0.161·corrected calf girth − 0.131·height + 4.5, where bone breadths are in cm and each girth is reduced by its skinfold ÷ 10. Ectomorphy uses the height-weight ratio HWR = height ÷ ∛weight: 0.732·HWR − 28.58 at 40.75 or above, 0.463·HWR − 17.63 between 38.25 and 40.75, and 0.1 below that. Each rating has a floor of 0.1, and the largest one names the dominant type. All ten inputs are required and must fall in plausible ranges: height 50–272 cm, weight 2–650 kg, each skinfold 1–80 mm, humerus breadth 3–15 cm, femur breadth 5–20 cm, flexed arm girth 10–60 cm and calf girth 15–70 cm. Anything outside shows no result.

Common mistakes

• Entering skinfolds in centimetres or bone breadths in millimetres. Skinfolds are in mm, breadths and girths in cm; a breadth typed as 70 (mm) or a skinfold typed as 0.8 (cm) falls outside the accepted range and shows no result, but a slip that stays inside the range goes through unnoticed.
• Using relaxed arm girth instead of the flexed and tensed arm girth that the method calls for.
• Entering the humerus and femur lengths instead of the epicondylar breadths (the width across the elbow and the knee). A femur length of about 45 cm is rejected, because the formula expects widths of a few centimetres.
• Pinching skinfolds at the wrong sites: each of the four skinfold fields needs a value taken at its own site, and a repeat measurement is worth taking.
• Reading the three numbers as a score out of 9; they are independent ratings, and the highest of them only names the dominant type.