If you’ve ever followed a crochet pattern to the letter and still ended up with a finished item that was either too big, too small, or just…off—you’re not alone. One of the sneakiest culprits behind unexpected results is something we often take at face value: yarn weight.

Today, we’re talking about #4 weight yarn, also known as medium weight. On the surface, it seems like a universal standard. But the truth is? #4 weight is actually a range—and the yarns within it can behave very differently.

The Experiment: One Pattern, Three Yarns

To illustrate just how much variation exists within the #4 category, I crocheted the exact same cup cozy pattern three times. I didn’t change a thing—same number of stitches, same number of rows, and the same 4.5mm crochet hook. The only difference was the yarn:

• ☁️ Caron Simply Soft (White)
• 🎨 Red Heart Super Saver (Tan)
• 🌿 Peaches & Cream Cotton (Dark Brown)

All are labeled as #4 weight, but the results speak for themselves.

The Results: A Cozy Size Showdown

Each cozy came out with noticeably different dimensions, textures, and stretch. Here’s a quick breakdown:

Caron Simply Soft (White)

• Soft and drapey
• Smaller and more compact due to finer strand (I had to add an extra row of SC stitches to match the height of the others!)
• Great stitch definition
• Slightly stretchy

Red Heart Super Saver (Tan)

• Thicker and sturdier
• Larger finished size, more structure
• Slightly rougher feel
• Stretchiest of all – will fit a wider range of cups

Peaches & Cream Cotton (Dark Brown)

• Dense and inelastic
• Widest of the three
• Absorbent material
• Lacks stretch – fits fewer cup sizes

What This Means for Your Projects

Even though each yarn claims to be #4 medium weight, their actual thickness, fiber content, and structure vary widely. That variation can significantly affect:

• 📏 Size and fit
• 🔄 Drape and stretch
• 🧵 Stitch appearance
• 🧼 Durability and washability

So, What Should You Do?

Whenever you’re following a pattern—especially for items that rely on size or fit—take these steps:

1. Check gauge (yes, it matters!)
2. Consider fiber type (cotton behaves very differently from acrylic)
3. Test with swatches before diving into the full project

And if you’re designing your own pattern? Be kind to your fellow crafters and recommend a specific yarn or give visual examples like this one!

Final Thoughts

The #4 label might look like a clear indicator, but it’s more like a general neighborhood than a specific address. Choosing your yarn carefully can make the difference between “meh” and “magic.”

Have you noticed big differences between yarns in the same weight class? Share your stories in the comments—or tag me on Instagram @ThePointedHat if you’ve done a similar experiment!

🧶✨ Crochet so good, it’s practically witchcraft.