A yarn comparison chart compares different types of yarns used for knitting. This chart compares the descriptive qualities of the yarn as well as the size of the needle recommended for use and how many wraps per inch a specific yarn can do.
The "tension" of any particular yarn is the amount of stitches and rows that are possible over a 10-centimeter, stocking-style stitch pattern. Needle sizes in yarn comparison charts are usually labeled with a metric measurement and must be converted. Wraps per inch signifies the amount of times a particular yarn can be wrapped around an inch of a ruler. This measures the yarn's thickness, rather than its length.