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Understanding Crochet Thread Sizes

  • 4 min read
Crochet hook on wooden background - Thread Collective Australia
Crochet hook on wooden background | Photographer: Meliha Gojak

Crocheting is a popular craft that allows you to create beautiful and intricate designs using thread. However, if you're new to crochet, understanding the different crochet thread sizes can be a bit confusing. In this article, we'll break down the basics of crochet thread sizes to help you choose the right one for your projects.

Why Thread Size Matters

Thread size plays a crucial role in determining the outcome of your crochet project. It affects the overall look, feel, and drape of your finished piece. Using the wrong thread size can result in a project that is too loose or too tight, making it difficult to achieve the desired stitch definition and texture.

The Different Crochet Thread Sizes

One of the most common ways to categorize crochet thread sizes is by using the number system. In this system, threads are assigned numbers that correspond to their thickness. The general rule is the higher the number, the thinner the thread. For crochet cotton, some common thread weights include size 3, size 10, size 20, and size 30.

  • Size 3: This is the thickest crochet thread and is often used for projects like rugs, baskets, amirugumi, and a variety of home decor items. Because of its thickness, it works up faster than finer threads and is an excellent option for those new to crocheting with thread.
  • Size 5:This is still a thick crochet thread but slightly thinner than size 3.It is suitable for making tablecloths and doilies. The thicker thread gives your projects a sturdy and substantial feel.
  • Size 10: One of the most popular choices among crocheters, size 10 is versatile and great for doilies, garments, bedspreads, curtains, and many other projects. This is a good size to start with for beginners.
  • Size 20:Thinner than size 10, this is excellent for delicate lacework, heirloom projects, and fine accessories. Due to its fine nature, it can be more challenging to work with, but the results are worth the effort.
  • Size 30: Among the thinnest, size 30 is perfect for extremely delicate and intricate crochet projects, including fine lace and doilies. Crocheting with size 30 thread requires skill and patience due to its fine texture.
  • Size 40: This is one of the thinnest crochet thread weights available. It is used for the most delicate and intricate lace crochet work.
Crochet Thread Sizes Weight Category UK Hook Sizes Metric Hook Sizes Yarns
Size 3 3 Light / Light Worsted 0 - 2 8.00mm - 7.00mm
Size 5 2 Fine / Sport Weight 3 - 6 6.5mm - 4.75mm
Size 10 0 Lace / Thread 6 - 8 5.00mm - 4.00mm
Size 20 0 Lace / Thread 9 - 11 3.5mm - 3.00mm Malabrigo Lace - 2 Ply 
Size 30 0 Lace / Thread 10 - 12 3.25mm - 2.5mm
Size 40 0 Lace / Thread 11 - 13 3.00mm - 2.25mm
Size 60 0 Lace / Thread 12 - 13 2.75mm - 2.25mm
Size 80 0 Lace / Thread 13 - 14 2.25mm - 2.00mm
Size 100 0 Lace / Thread 14 2.00mm

Crochet thread sizes and compatible hook sizes.

Please note that the chart above is only a general guide with approximates as crochet thread sizes can vary between manufacturers. We advise that you follow the crochet hook recommendation on your yarn labels.

To learn more about standard yarn weights and how to find the equivalent yarns for crochet, please read our guide.

Understanding Crochet Yarn Labels

When shopping for crochet threads, it's important to read the labels carefully as they provide valuable information about the thread size. Here are some key terms you'll find on crochet yarn labels:

  • Weight Category: This indicates the crochet yarn or thread weight category (e.g., lace, fingering, sport, etc.).
  • Recommended Hook Size: The suggested hook size to use with the crochet thread.
  • Gauge: The number of stitches and rows that should be achieved in a 4x4 inch (10x10 cm) swatch using the recommended hook size.
  • Yardage/Meterage: The length of crochet thread in yards or meters.

By understanding these terms and referring to the label, you can select the appropriate thread for your crochet project.

Tips for Choosing the Right Crochet Thread

A young girl with long blond hair knits a yellow sweater in the garden in the summer. | Photographer: Jula
A young girl with long blond hair knits a yellow sweater in the garden in the summer. | Photographer: Jula

Here are a few tips to help you choose the right thread size for your crochet projects:

  1. Choose your project carefully. Determine what you want to create. Thicker threads are suitable for sturdy items like tablecloths, while finer threads work well for intricate lacework.
  2. Consider pattern recommendations. If you're following a crochet pattern, check if it specifies a particular thread weight. Following the pattern recommendations will ensure that your finished project turns out as intended.
  3. Experiment with swatches. Before starting a large project, create a small swatch using different hook sizes and thread weights to see how they affect your stitch definition and overall fabric drape.
  4. Go with your personal preference. Ultimately, choosing a thread size comes down to personal preference. Some crocheters prefer working with thinner threads for delicate projects while others enjoy using bulkier options for quick results.


Understanding crochet thread sizes is essential for achieving successful crochet projects. By familiarizing yourself with different weight categories and reading labels carefully, you can confidently choose the right crochet thread size for each crochet project. Remember to consider pattern recommendations and experiment with swatches to find what works best for you. Happy crocheting!

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