In the apparel engineering and construction process, the Size Grading Logic provides the logic for different sizes. The tech pack for clothing is a mathematical bridge that ensures a design remains consistent for different sizes from SMALL to Extra Large. The SGL is not just a matter of scaling a garment “up” or “down,” but it is a complete manual of stitching. The SGL is a strategic calculation of how volume and length should be distributed as the body grows.

The Philosophy of Non-Linear Grading

The SLG is not a simple enlargement of a garment from small to large. SLG size starts from SMALL to Large. For example, there is not only a 10 % difference between the two sizes, but it is not usually consistent across the Small to Large sizes.

• SLG Consistency: The SLG measurement manual is prepared with consistency as desinger knows that human bodies do not grow uniformly. So it has proportional measurements across the bodies. Just understood by a simple example that a person’s chest circumference increases independently of different portions of the body. Neck width or wrist circumference does not necessarily grow at the same rate. 
• Grade Rules in SLG: The SLG defines the Grade Rules applied to each Point of Measure (POM). SLG provides the measurement specification for a specific design. So SLG maintains the “style sense” of the original sample.

Base Size: The Anchor Point

The logic always starts with the Base Size in a tech pack for clothing. It is usually a Medium or a Size 8, and all the sizes are built. It has been physically fitted and approved by the tech designers. SLG establishes base “increments” for other sizes, done by proportional measurement rules for other garment sizes. 

• Length Grading: The SLG usually follows a smaller increment for each size(e.g., +1cm per size). Different widths are often similar in height, so a proportional rule is applied in the SLG booklet.
• Girth Grading: For the volume or the girth of the designs, the SLG follows larger increments (e.g., +4cm or +5cm per size).SLG prepares and accommodates body volume.

Digital Grading

SLG grading and the logic have evolved from manual spreadsheets to the Biometric AI Grading system. Designers use databases of thousands of body scans to accommodate the target market’s clothing sizes. The precise tech pack for clothing can produce a proportional increase or decrease in the sizes. So they can predict how their target demographic actually changes. 

Standard Grading Logic: Alpha Sizing (S–XXL)

Take Away:

In this way, a brand can present different products for different sets of the target market. A brand can present and target “Athletic Fit” vs. “Plus Size.” SLG grading logic completely different for various sizes of the target audience. The AI helps the designer ensure that a 2XL hoodie has the same aesthetic “oversized” look as the Medium, rather than just becoming a giant, shapeless tent.