“The factory kept tweaking individual sizes. Nobody was managing the size range.”
Where the client started
The legging had solid reviews in S and M. The original factory extended it to XS, XL and 2XL with a fixed grade rule. Try-ons told a different story: horizontal creasing at the XS front rise, waistband sink at the back of XL, and thigh pressure on 2XL clearly higher than at the waist. The factory offered to “add a bit here, remove a bit there” — with no account of what each tweak did to the system.
How SEAMDANCE handled it
We treated the base size as one input, not the standard — re-examining the relationship between body measurements, garment measurements, the fabric's usable stretch and the target compression feel. Try-on feedback from wearers across the range was converted into comparable data: front-back rise difference, crotch length, hip, thigh, and extension percentages at key points.
Round one stabilized the XL back waist, but 2XL knees stayed tight. Round two didn't enlarge the whole garment — it changed how thigh girth grows in the extended segment, moved the knee position, adjusted fabric direction and kept the waistband support. Edge-size approval added standing, deep squat, lunge and seated tests instead of front-and-side photos only.
Reference outcome
The result is segmented grading logic rather than mechanical scaling from M. The client also accepted an honest truth: wearing pressure can't be identical across sizes, but support, coverage and range of motion at the key positions can be held to standard. When new colors were added later, nobody had to re-argue every size again.