Body & frame
Clavicle Width
Collarbone length, the bone that sets shoulder frame width. Fixed in adulthood — but visual width is bone plus delts plus lats, and two of those train.
What Clavicle Width means
Clavicle width — in practice biacromial width, the distance between the two acromion processes — is the skeletal measurement community talk treats as the ceiling on how wide your shoulders can ever look. Adult male biacromial width clusters around 39-42 cm, and it stops changing once the medial clavicular epiphysis fuses; that is one of the last major growth plates to close, usually by the early-to-mid twenties. Forum advice to 'measure your clavicles' means this bone-to-bone span, though most people actually measure delt-to-delt and overstate their number by several centimeters.
What it actually does to the first impression
What a first glance reads is total silhouette width at the shoulder line — bone plus muscle plus fabric — never the bone alone. That matters because the trainable share is large: developed side delts add real centimeters per side, and lat width rewrites the whole upper-torso outline from the front and the back. A narrow-clavicle man with trained delts routinely out-silhouettes a wide-clavicle man who doesn't lift. The bone shows most in tank tops and shirtless photos, where deltoid mass can't fully disguise the span underneath.
Reality check: the forums vs the data
The community is right that the bone is fixed and right that it matters; it's wrong about the ratio of fixed to fillable. The gap between average and genuinely wide biacromial width is a few centimeters — deltoid and lat development can swing visual width by more than that, and a tailored shoulder seam fakes another centimeter or two on top. Where the cope fails: shirtless, at low body fat, bone span does read. So the move is maximizing the trainable layer, not mourning the layer underneath it.
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Related terms
Reference data on this site