shoulderwidth

Shoulder width, or biacromial breadth, is the horizontal distance between the left and right acromial processes—the outer edges of the shoulders. It is a standard anthropometric measurement used to characterize body width and to inform design and assessment across fields such as clothing, ergonomics, and medicine.

Measurement is typically performed with the subject standing upright and the arms at the sides. The distance between the most lateral points of the shoulders is recorded using a sliding caliper, anthropometer, or a 3D body scanner. Standardized positioning reduces variation due to posture or arm position; measurement should be taken on the same plane, usually across the upper back.

Shoulder width varies with sex, height, overall body size, age, and ethnicity. It is largely determined by skeletal structure and changes little after late adolescence, though soft tissue and posture can influence apparent width. In clinical or sports contexts, accurate measurement is important for sizing prosthetics, equipment fit, and performance assessment.

In apparel and apparel engineering, biacromial breadth informs pattern drafting, fit, and sizing. In equipment design, it affects helmet and backpack dimensions, straps, and load distribution. In ergonomics and seating, shoulder width helps determine chair backrest width and upright posture guidance. It also serves in research on body proportions and in normative databases.

See also: Anthropometry, Acromion, Biacromial diameter.