The equation to calculate Wraps per Inch (WPI) is as follows:

WPI = Total number of wraps / Length of sample in inches

WPI Calculator

What is WPI Tool in Yarn?

The WPI tool (Wraps per Inch) is essential for knitters and weavers. It helps to measure the thickness and gauge of yarn accurately. Knit Crafters can determine the weight and thickness of a yarn sample by calculating the number of wraps per inch.

How to Calculate WPI?

To calculate Wraps per Inch (WPI), you need a ruler or measuring tape and a sample of the yarn you want to measure. Follow these steps:

1. Prepare the sample: Take a length of yarn at least 1 inch (2.54 cm) long. It’s better to have a more extended sample to ensure accuracy, but 1 inch is the minimum.
2. Wrap the yarn: Start wrapping the yarn tightly and evenly around the ruler or measuring tape, ensuring the wraps are side by side and not overlapping. Keep the wraps snug, but don’t stretch the yarn.
3. Count the wraps: Count the number of times the yarn wraps around the ruler or measuring tape within 1 inch. Make sure to count only complete wraps and not partial ones.
4. Calculate WPI: Divide the total number of wraps by the length of the sample in inches. For example, if you counted 13 wraps in a 1-inch sample, the WPI would be 13.

Remember that WPI measures the thickness or density of the yarn. Higher yarn WPI values indicate thinner or finer yarn, whereas lower WPI values indicate thicker or bulkier yarn.