I'm designing a new cowl and mitt set. The intent is for each (cowl and mitt set) to use a single 100g skein of worsted weight yarn. I love not having lots of leftovers -- just enough for an emergency repair.
I recently finished the prototype cowl and had just enough left over -- not enough to knit another round! Perfect.
Since the cowl features a border on both the top and bottom, I had to calculate how much yarn was needed for the border so I knew when to stop knitting the body. My rule of thumb is as follows:
(diameter of needle x pi x number of stitches/row x number of rows x 150%) / 1000 = meters of yarn required