Measure your wrist, enter your height, and see which frame category you fall into.
Estimates are for general guidance only and are not medical advice. For a personalised plan, book a free guided tour at RPM Gym.
What this measures is frame size. Wrist circumference relative to height is a reasonable proxy for skeletal width, because the wrist carries almost no fat or muscle — which is exactly why it's the site used.
The labels are ectomorph, mesomorph and endomorph, because that's the language people search with. They come from William Sheldon's 1940 somatotype system, which classified physiques and then linked them to personality traits. The personality half was abandoned decades ago. The physique descriptions survived into fitness culture, largely detached from the research that produced them.
So read your result as a description of your skeleton, not a diagnosis of your metabolism. A narrow frame doesn't mean you struggle to gain weight, and a broad one doesn't mean you gain fat easily. Those are claims about energy balance, and a wrist measurement has no access to them.
| Ectomorph | height ÷ wrist above ~10.4 (men) or ~11.0 (women) | Narrow skeletal frame for your height. Says nothing about how you respond to food or training. |
|---|---|---|
| Mesomorph | between the two thresholds | Mid-range frame. The most common result, and the least informative. |
| Endomorph | below ~9.6 (men) or ~10.1 (women) | Broader skeletal frame for your height. Not a statement about body fat. |
Index = height (cm) ÷ wrist circumference (cm) Men: > 10.4 narrow · 9.6-10.4 mid · < 9.6 broad Women: > 11.0 narrow · 10.1-11.0 mid · < 10.1 broad
A man of 183 cm with an 18.5 cm wrist.
Mid-range frame, which is where most adults land. Note what has and hasn't been established: his skeleton is average width for his height, and nothing at all is known about his metabolism, his training response or what he should eat.
Frame size is real and measurable. The three-type system layered on top of it is a simplification of a 1940s classification whose main claim — that physique predicts temperament — was discarded. Physique varies continuously, and almost nobody is a pure type.
Measure your wrist at its narrowest point and divide your height by it. That gives a frame-size index, which is what these calculators are actually computing when they report a somatotype.
Not because of the label. Calorie needs differ by body size, activity and training load, all of which are measurable directly — so measure them. Two people with the same somatotype can have maintenance levels several hundred calories apart.
You can change your body composition substantially and your skeletal frame not at all. Someone with a narrow frame who trains and eats for years will look very different from their earlier self while their wrist measurement stays where it was.
Because the middle band is wide and most adults fall in it. That's a feature of how the thresholds were drawn rather than a finding about the population, and it's a good reason not to read much into a mid-range result.
Training and nutrition are set by your goal and your progress, not by a category. Work out where to start on a free guided tour at RPM Gym in Al Manhal.