A 20-inch shoulder width measurement is often used to assess physique and set fitness goals. Whether this measurement is considered “wide” depends heavily on the individual’s overall body frame, height, and gender. This measurement indicates upper body development, but its significance is best understood when compared to general population averages and personal body proportions.
Understanding How Shoulder Width Is Measured
Shoulder width measurements refer to two distinct anatomical points: biacromial breadth and bi-deltoid width. Biacromial breadth measures the distance between the two acromion processes (the bony points at the end of the collarbone and shoulder blade). This measurement represents the skeletal frame and is primarily used in anthropometry for body-size classification.
The 20-inch measurement typically discussed in fitness contexts refers to the bi-deltoid width. This is the maximum horizontal width across the shoulders, measured to the outermost protrusion of the deltoid muscles. Since the deltoid muscles sit outside the bone structure, this measurement includes the soft tissue and muscle mass that contributes to the visible breadth.
To accurately measure bi-deltoid width, a measuring tape should be stretched straight across the back, from the widest point of one shoulder to the other. The subject should stand relaxed with arms hanging naturally. It is important to ensure the tape is level and does not dip or angle, which would result in an inaccurate reading.
Contextualizing 20 Inches: Comparison by Gender and Height
A 20-inch shoulder width is significantly above the average for most adult populations, particularly when the measurement is the muscular bi-deltoid width. For American men, the average biacromial breadth—the bony width—is approximately 16.1 inches. Twenty inches still places an individual well into the upper percentile of the male population.
For men, a 20-inch shoulder width is often considered broad, approaching the size of competitive bodybuilders or athletes with a highly developed upper body. In contrast, the average biacromial breadth for American women is roughly 14.4 inches. A 20-inch measurement for a woman would be exceptionally wide, representing a rare frame size or a very high degree of muscular development.
The perception of this measurement is also heavily dependent on the individual’s height. A 20-inch width on a person who is 5 feet 6 inches tall will appear dramatically wider than on someone who is 6 feet 4 inches tall. Shorter individuals with this measurement are perceived as having an extremely broad frame due to the greater width-to-height ratio. The same width on a taller person may be perceived as proportionate, as the overall vertical frame accommodates the horizontal expanse.
Factors Influencing Perceived Width
The visual impact of a 20-inch shoulder width is not solely determined by the number on the tape measure, but by the surrounding body composition and shape. The development of the lateral and posterior heads of the deltoid muscle is directly responsible for the roundness and width that contributes to the bi-deltoid measurement. A measurement of 20 inches achieved primarily through muscle mass will appear much more defined and athletic than if it were due to higher body fat distribution around the upper arm and shoulder area.
A low body fat percentage enhances the visual definition of the shoulder muscles, making the clavicle and the contours of the deltoids more apparent. This clarity makes the shoulder width stand out more effectively. Furthermore, the perceived width is greatly exaggerated by the V-taper, which is the proportional difference between the shoulder width and the waist circumference. A narrower waist creates an optical illusion, making the shoulders appear substantially broader than they might otherwise look.
Strategies for Modifying Shoulder Width
Individuals aiming to achieve or enhance a 20-inch shoulder width must focus on maximizing the size of the deltoid muscles, particularly the medial (side) head. Since the skeletal width, or biacromial breadth, is determined by genetics and cannot be altered through exercise, the only way to increase the bi-deltoid measurement is through muscle hypertrophy. The lateral deltoids are the primary muscle group responsible for providing the outward width to the shoulder frame.
Specific isolation exercises, such as the dumbbell lateral raise and cable lateral raise, are highly effective for targeting the lateral deltoid. These movements focus on shoulder abduction, the act of lifting the arm away from the body, which is the main function of the side deltoid. Training the posterior deltoid with exercises like face pulls or reverse flyes is also important for a balanced look. Consistency in resistance training, coupled with adequate protein intake, provides the necessary stimulus for muscle growth.