. So here's how it works. The "g" stands for grams. 100g are about 3.5 oz. So you would need 2 of the 50g skeins to equal the 100g you need. BUT. . .it depends on the yardage. In order for your project to come out right, you need to have be using the same weight of yarn. If you need 100g that give you 700 yds, and you want to substitute that with 2 skeins of 50g that get 200 yds each, that's going to be a problem, because then you'll get 400 yds of yarn for your 100g-- and that will be a much thicker yarn (the thinner the yarn, the more yards you get per gram or ounce). So it's fine to use 2 of the Knitpicks, as long as the yardage is roughly the same. What yarn does the pattern call for, and what is the yarn from Knitpicks?