How frame size is estimated
Wrist circumference is a convenient proxy for bone thickness because there is little fat or muscle there. By dividing your height by your wrist measurement, this tool produces a ratio that reflects how slender your skeleton is relative to your stature.
A higher ratio means a thinner wrist for your height, which maps to a smaller frame; a lower ratio points to a larger frame. The thresholds differ slightly between men and women.
Frame size and somatotype
The result labels your frame as small, medium or large, and attaches a rough somatotype: ectomorph (lean, small frame), mesomorph (medium, athletic) or endomorph (larger frame). Treat the somatotype as a friendly description rather than a precise category.
Frame size is most useful as context for other tools. Two people of the same height and weight can have very different builds, and frame size helps explain why an ideal-weight figure might sit higher or lower for you.
Using the result well
Keep a few things in mind when interpreting your frame:
- Measure the wrist just below the bony bump, on the hand side.
- Frame size does not change with diet or training — bone structure is fixed.
- It says nothing about fat or fitness; pair it with a body-fat estimate.
- Borderline ratios can flip categories, so treat the label as approximate.
Health note
Somatotyping is an old, broad classification and this tool treats it as an approximation, not a clinical or scientific measurement. For guidance on healthy weight or body composition, consult a qualified professional.
Formula
ratio = height / wrist (both cm); thresholds vary by sexFrequently asked questions
- Is somatotype scientific?
- Somatotyping is an old classification and is treated here as a friendly approximation, not a precise medical measure.