The guage given in the pattern is 18 sts & 24 rows = 10 x 10 cm. The pattern book is Lopi #28 and I'll be knitting the Riddari sweater.
Would it be worth it just to go ahead and order the Karisma and then just knit a few swatches?
I just have no idea how to adjust gauges, especially when working with a pattern, so if someone can explain the thought process of figuring that out, I would be ever so grateful!
edit:
the other sizes are chest: 93, 98, 102, etc cm, if that helps.