Substitute Yarn

Have you ever experienced want to make something badly, but we don’t have yarn required in the pattern? I experienced that many times, but I always manage to find the substitute yarn on my stash using this guide:

2 strands fingering weight (#1) = 1 strand sport weight (#2)
2 strands sport weight (#2) = 1 strand worsted weight (#4)
2 strands worsted weight (#4) = 1 strand bulky weight (#5)