Have you ever come across the term "wraps per inch" but felt unsure about what it means? Or perhaps you have some idea but still find it confusing? Today, I aim to clarify this term and show you how to use it to your advantage when shopping for yarn, whether online or in-store.

What is Wraps Per Inch?

Wraps per inch (WPI) is a method of measuring the thickness of a strand of yarn. By wrapping the yarn around a ruler or similar tool, you count how many times the yarn fits within an inch. This gives you the WPI, which helps you compare yarns of different types and origins.

Yarn classification systems can be complex and vary by region:

Ply System: In the UK, Australia, and New Zealand, yarn is often classified by the number of plies (threads) twisted together. However, the number of plies doesn't always correlate directly to the yarn's thickness, as the thickness of individual plies can vary.

Weight System: In the US, yarn is categorized by weight classes such as lace, super fine, fine, light, medium, and bulky. These terms describe the thickness and weight of the yarn rather than the number of plies.

As you can see, these systems can be confusing. This is where wraps per inch come in handy. WPI helps crafters understand exactly what type of yarn they are working with, regardless of regional naming conventions.

Below is a yarn chart to help you understand and use as a reference.

 Conclusion

As you can see from the chart, there is significant overlap between different yarns. This is because not all yarns are created equal. A yarn with fewer plies can sometimes be just as thick as a yarn with more plies. This variability makes WPI a valuable tool for accurately assessing yarn thickness across different types and regions.