Is this yarn DK or worsted weight? Find out with the WPI Tool! The WPI Tool is a handy device for all fiber artists who want to measure their fiber's WPI (wraps per inch). Increasingly, WPI is being used by designers and yarn manufacturers when specifying yarn characteristics. Two yarns that have the same WPI can be exchanged. This is important if you are trying to substitute one yarn for another in a given pattern.

The WPI Tool is made from birch hardwood which has an oil finish applied. The tool measures 5" in length x 5/16" diameter (yarn guide knob measures 5/8"). All markings are laser etched into the wood and will not wear off. There are markings for up to 3 inches which allows you to calculate a more accurate average WPI on certain hairy yarns, and there are also 1/2 inch marks. A special yarn guide knob is used to hold your yarn in place while measuring the WPI. A special WPI Knit-Kard? comes bundled with the tool in a ziplock bag. The Kard tells the user how to use the tool and provides a useful WPI chart for 6 different weights of yarn.