Names vary by market
Labels such as DK, worsted and aran are useful categories but not perfectly interchangeable across brands and regions. Metres per weight and recommended gauge provide additional evidence.
Fibre changes behaviour
Wool, cotton and synthetic blends can drape, stretch and absorb differently even at similar thickness.
Swatch before substituting
A substitute should meet fabric and gauge needs, not only a category name. Make and wash a swatch in the intended stitch.
Practical checklist
- Keep the original pattern's total length requirement.
- Check care instructions before combining yarns.