Definition
Pattern grading is the process of scaling a base pattern up and down into a range of sizes, by set amounts at specific points of each piece.
A pattern company drafts and tests one sample size, then grades it: each point of each piece moves by a fixed increment per size, according to grade rules. Typical grades in the middle of a women's range are about 4 to 5 cm (1 1/2 to 2 in) per size at bust, waist and hip, with smaller steps at the shoulder, neck and length, and often larger jumps in the bigger sizes.
Grading is not like enlarging a photo. Bodies do not grow uniformly: a larger size is not proportionally taller, and shoulders change much less than hips. That is one reason standard sizes fit some people well and others poorly, and why sizes from different brands rarely match.
Sewists use the word in two ways:
- Grading between sizes, or blending: drawing a smooth line from one size at the bust to another at the waist or hip on a nested-size pattern.
- Grading seams, a different technique: trimming seam allowances to different widths (see grading seams).
Made-to-measure patterns skip grading: instead of picking the nearest size and adjusting it, the pattern is drafted from your own measurements. Sewly offers both, a standard size (women EU 32–54, US 0–22, UK 4–26; men XS–3XL; children 2–14 years) or your own measurements. See how to choose your size.