Even though this particular example is for sock yarn, you can use this same proportion to determine the length of any remaining yarn of any weight, so be sure to bookmark it if this concept is new to you.

There are many great patterns out there for using sock yarn leftovers, but I hope you'll check out my new pattern: Mug Snug.  The pattern is $5.00 on Ravelry, but subscribers to my newsletter will receive a coupon code for a free download of Mug Snug.