Each manufacturer sets both their base pattern and grading measurements in order to meet the desired sizing for the target audience. Each pattern has a defined range of sizes for a single apparel style. Grading does not change the style or shape of a pattern but merely increase or decrease the size of it. Grading also reflects the fact that different sizes are proportionately different, not uniformly.
Once the approved average is sized (typically size 8), the pattern will follow a set of "grade rules". These grade rules allow for the manufacturer to systemically increase or decrease the middle-sized pattern based on the desired size, essentially a size chart.
Top Notch offers to precisely grade patterns based off custom specifications. Not sure on what sizes to choose? Talk to us about the industry standards!