Kathy's Kreations

Below is the "Standard Yarn Weight System", showing the symbols that yarn companies will be printing on labels attached to yarn skeins.  Although only a guideline, they should help eliminate some of the confusion with yarn sizes.
Source:  Craft Yarn Council Of America

Standards & Guidelines For Knitting And Crochet

Standard Yarn Weight System
Categories of yarn, gauge ranges and
recommended needles and hook sizes

print this chart   {in PDF format}

*Guidelines Only:  The above reflect the most commonly used gauges and needle or hook sizes for specific yarn categories.