Finding a substitute yarn
I want to knit an old 80s pattern that requires a discontinued yarn (3 Suisses Lorena). I believe this is similar to an Aran or Worsted weight. The yarn gauge is 20 sts and 24 rows on Size 7 needles. I know I can adjust needle size after knitting a swatch of my chosen yarn, once bought, but I don't understand how I can choose the right yarn to buy in the first place. Will a yarn that states 19 sts and 25 rows on size 7 be close enough? How does that compare with one that states it will knit 18 sts and 24 rows on size 8 needles? Is there a gauge converter that shows equivalent sts and rows for different needle sizes to use as a reference when looking at tension guides on labels? I'm worried that I may end up buying a yarn with which I can work out the needle size for the correct number of stitches to 10cm, but I get a different row count. The pattern is too complicated for me to start trying to adjust the length of the work to get the right measurements. I hope you can help.