Body composition calculator
Somatotype calculator
Your Heath-Carter somatotype — endomorphy, mesomorphy and ectomorphy as three numbers, not one label. Free, instant, no sign-up.
A somatotype describes where you are, not what you can become. The coach handles the second part.
What is a somatotype?
A somatotype is three numbers, not one word. Endomorphy rates relative fatness, mesomorphy rates how robust your muscle and bone are for your height, and ectomorphy rates linearity — how stretched out your mass is. Everyone has all three, and a somatotype is written as the three ratings in that order, so 3-5-2 describes someone moderately fat, strongly built and not especially linear. The single most common misuse of this idea is treating it as three boxes to be sorted into.
Where the ectomorph-mesomorph-endomorph idea came from
William Sheldon coined the three terms in the 1940s as part of a constitutional psychology which claimed that body shape predicted temperament — that thin people were anxious and intellectual, muscular people assertive, and heavy people relaxed and sociable. That theory does not survive contact with evidence and has been abandoned for decades. Heath and Carter's contribution in the 1960s was to keep the three-component description of physique, throw out the personality claims entirely, and replace Sheldon's photographic rating with an anthropometric method anyone can reproduce with calipers and a tape. What this page calculates is a measurement. It says nothing about your character, and it does not tell you what you are capable of.
How this calculator works
Endomorphy comes from the triceps, subscapular and supraspinale folds, summed and corrected to Carter's 170.18 cm reference stature so a tall and a short person with the same folds are not rated differently for a reason unrelated to fatness, then run through a cubic polynomial. Mesomorphy combines the two bone breadths with the arm and calf girths, and subtracts height. Crucially, each girth has the overlying skinfold subtracted first — arm girth minus a tenth of the triceps fold, calf girth minus a tenth of the calf fold — so the rating reflects muscle and bone rather than the fat sitting on top of them. That correction is the step hand calculations most often get wrong. Ectomorphy comes from the height-to-weight ratio through a piecewise formula with breakpoints at 40.75 and 38.25.
What it is actually good for
Somatotyping earns its keep in sport science, where physique profiles differ sharply and consistently between events — throwers and rowers sit high on mesomorphy, distance runners high on ectomorphy, and the pattern holds across countries and decades. It is a useful descriptive tool for tracking how an athlete's physique changes over a season or a career. What it is not good for is prediction about an individual. Ratings shift substantially with training and diet, the components are not destiny, and knowing your three numbers tells you nothing about which sport you should play.