I have been spinning for almost a year now, and I’ve heard some rumblings about Wraps Per Inch (or WPIs). There are many ways to measure WPI, including simply wrapping your yarn around a ruler or a note card or even a pencil that has 1″ marks (you’re going for width of yarn, so the size of the measuring object is unimportant); you wrap one strand next to the next (without overlapping) and then count the number of strands in the space of an inch. The number can be converted to a yarn gauge. Some hand spinners care about this kind of measurement, others couldn’t care less . . .
For knitting projects, the Wool Festival has a terrific chart that uses WPIs as a guide for buying (enough) yarn without a specific project/pattern in mind.
The cool thing is that WPIs can be used for handspun OR for mystery yarns in your stash–wrap, measure, and voila! That mystery yarn is a mystery no more! It’s lace weight or DK weight, etc.
Last week, I fell victim to the wiles of the internets and gave in to a lovely WPI measuring device from Hipstrings that takes some of the struggle out of measuring WIPs . . . and I am super excited about checking my hand spun against this little tool! I do believe that many spinners would still recommend the old wrap and count, but this is a nice “Spinners Control Card” for use while spinning; it will give you a quick measure of the width of your yarn in comparison to some basic standards.