Yes WPI can be deceiving, a thin fuzzy yarn like mohair will wrap as if a fingering weight, but is often knit in a worsted or bulky gauge because the fuzz fills in the stitches. And wpi charts often don’t agree, especially on either end of the ranges. So while it can be handy for an estimate, it’s not absolute.
If the yarn has a gauge and needle size on the label, that can be a better way to go. This gauge is used to classify the yarn into the weight range, but the needle size is the key. Worsted is usually shown as a 7 or 8 needle, aran a 9, bulky 10, dk 5 or 6 and sport has a 4 or 5 needle. Fingering usually shows more range in needle sizes because it can be knit on size 1 or 2 for socks which need to be densely knit, or a size 3 or 4 for regular knits, though you can use larger needles for a lacey item. Same thing with laceweight, a needle size and gauge isn’t usually given because it’s mostly knit with larger needles (size 4 to 8) for lace patterns.
I acknowledge the comments of the moderator below and acquiesces and thereby deleted the original post.
I acknowledge the comments of the moderator and acquiesces and thereby deleted the original post.
Now they’re gonna wonder what you said… lol