Course Density and Wale Density

Course Density and Wale Density

What is course density? It refers to the number of courses (horizontal rows of loops) per unit length along the fabric’s lengthwise direction. Conversely, wale density refers to the number of wales (vertical columns of loops) per unit length along the fabric’s widthwise direction. Imagine a piece of fabric hanging vertically: the horizontal rows of loops—like the horizontal stroke in a plus sign (“crossbar”) —form courses, while the vertical columns of loops—like the vertical stroke (“downstroke”)  —form wales.

To illustrate with an analogy: on a standard globe, the top represents the North Pole and the bottom the South Pole. Lines connecting these poles are meridians (longitudinal lines), whereas the equator wraps around the middle like a “swim ring” and is a classic example of a parallel (latitudinal line). Circular knitting machines are weft-knitting machines: yarn is fed circumferentially—much like a line of latitude—and with each full rotation of the machine, one course is knitted.

Thus:

One revolution = 1 course

N revolutions = N courses

Course density is expressed as courses per inch (CPI) and reflects the fabric’s thickness and weight (GSM).

Wale density is expressed as wales per inch (WPI) and indicates how tightly the fabric is structured and its elasticity.

Examples of Course Density (CPI):

40 CPI = lightweight and thin

60 CPI = medium weight

80 CPI = thick and high GSM

Examples of Wale Density (WPI):

18 WPI = loose structure

28 WPI = medium density

36 WPI = tight structure, higher quality

Here, GSM (grams per square meter) is the key metric for evaluating the weight of knitted fabric and is directly influenced by CPI and yarn count.

Interestingly, a similar logic applies to a paper notebook: the space between two horizontal lines constitutes a row, typically used to write a complete piece of information. If vertical lines are present—as in grids, planners, or schedules—the space between two vertical lines forms a column, used to categorize similar types of data. Although the medium differs, the structural principle remains consistent across systems: rows run horizontally, columns run vertically—whether in fabric or spreadsheets.

Conclusion:

Understanding course density (CPI) and wale density (WPI) is not only fundamental to mastering knitting technology but also essential for precisely controlling a fabric’s hand feel, weight, and functional performance. Just as warp and weft threads interlace to create cloth, and data points align to form tables, structured thinking allows us to discern essence amid complexity. Whether weaving a textile or organizing information, it is direction and density that ultimately define texture, quality, and order.