A wpi tool, or “wraps per inch” tool is used by spinners to identify the weight type of your new spun yarn.
Wrap the yarn around the slot in the wpi tool (which is an inch). The yarn should be snug, and the wraps should lay side by side without any over lapping, or large gaps between strands.
In this table made by the Craft Yarn Council you can look up very useful information regarding to your just measured wpi!
|Dimensions||8.5 × 5.4 × 0.3 cm|