The following are resources that may be helpful as you’re planning your projects or working through a pattern.

This chart of yarn weight and needle sizes is really handy to figure out which yarns you might be able to substitute in a pattern, which names for sizes are synonyms, and which size needles are likely to be a good fit.

This chart provides an estimate of how much yarn you’ll need of each size in order to make different projects. I find this to be useful if I’m at a yarn store and see yarn I want to get for a project (such as a blanket or scarf) but don’t yet have a specific pattern in mind.

Sometimes a pattern will have the list a knitting needle or crochet hook size in millimeters, but we’re more used to looking at the U.S. number assigned to that size. This chart gives those conversions.