If I have 250 yards - 50 grams per ball -10 balls how do I know if worsted weight - fine -sport- ect. Without seeing it?
You can probably make a guesstimate using this chart:
A lot depends on what it’s made out of.
I looked at a ball of WOTA, which is worsted, and it has 110 yards to 50g.
I have a ball of fingering weight wool which has 230 yards per 50g.
Cotton would be heavier, thus less yardage; other yarn might be lighter and get more yardage.