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How to Do the Wrap Per Inch (WPI) in Crochet

Wrap Per Inch (WPI)

Choosing the right yarn for a crochet project is essential, especially when the label is missing. One simple and effective technique to determine yarn weight is the Wrap Per Inch (WPI) method. This guide will teach beginners how to do the Wrap Per Inch (WPI) in crochet so they can confidently select the best yarn for their project.

What is Wrap Per Inch (WPI) in Crochet?

  • WPI stands for Wrap Per Inch – a technique used to measure the thickness of yarn by wrapping it around a tool and counting the wraps within one inch.
  • This method helps classify yarn weight when the label is missing.
  • It is widely used by crocheters, knitters, and spinners.
  • WPI standards are available on most yarn labels, making this an accurate method to compare unknown yarns.

Why Use the Wrap Per Inch (WPI) Method?

  • Wrap Per Inch Purpose: Helps crocheters determine yarn weight without a label.
  • Avoids guesswork when substituting yarn in a pattern.
  • Useful for organizing leftover or mystery yarns in storage.
  • Works for all fiber types, including wool, cotton, and acrylic.

How to Do the Wrap Per Inch (WPI) in CrochetMaterials Needed:Step-by-Step Process:

  • A smooth cylindrical object like a pencil, knitting needle, ruler, or dowel rod.
  • A ruler or measuring tape.
  • The yarn to be measured.
  1. Choose Your Tool: Select a smooth, even surface such as a ruler or knitting needle. Avoid textured surfaces to get accurate results.
  2. Wrap the Yarn: Hold the yarn firmly (but not too tight) and wrap it around the tool evenly, without overlapping or stretching it.
  3. Measure One Inch: Use a ruler or tape measure to mark a one-inch section of the wrapped yarn.
  4. Count the Wraps: Count how many times the yarn is wrapped within that inch.
  5. Compare with WPI Standards: Match the counted wraps to the standard WPI chart below to identify the yarn weight.
WPI Yarn Value

How to Use Yarn Without a Label

  • Use WPI to match yarn weight to labeled yarn in your stash.
  • Compare the texture and fiber content by feeling the yarn.
  • Make a small gauge swatch to check how the yarn behaves in stitches.
  • If substituting yarn in a pattern, match the recommended WPI for consistent results.

Additional Crochet Tips and Techniques

  • Keep a yarn journal with WPI measurements of all your yarns for future reference.
  • Store yarn with small handwritten labels to track its WPI and fiber content.
  • When using multiple yarns in one project, match their WPI for even stitch definition.
  • Experiment with different hook sizes to see how the yarn drapes before starting a project.


Understanding how to do the Wrap Per Inch (WPI) in crochet is an essential skill for all crocheters, especially beginners. Whether you have mystery yarn in storage or want to substitute yarn in a pattern, the WPI method ensures accuracy and confidence in your projects. By following this simple technique, you’ll never struggle with unlabeled yarn again!


Happy Crocheting! 

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