How to Pick Yarn for Your Knitting Pattern

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The first night at the ski lodge, my friend Carrie plopped down next to me with her knitting bag.

“Okay, here’s what I’m making,” she said as she unfolded a pattern she had downloaded. The design in the photo was a beanie in moss stitch and what looked like hand-dyed sock yarn. She pulled out a skein of worsted yarn and a pair of size 5 needles and, smiling at me, declared: “I just need help casting on!”

“Hmm,” I said, hesitating as I took the skein and turned it in my hand, pinching out one dense strand between two fingers. “First, we gotta talk about yarn substitution.”

“Are you saying this won’t work?” she said, crestfallen.

“Well, your yarn is thicker than the pattern and probably too thick for your needles,” I replied as I scanned the pattern for yarn info.

“How do you know that?”

Swatching is key to getting a great final project, but you only swatch when you think you have the right yarn for the pattern. This sounds like a lot of work, and I could tell Carrie was feeling overwhelmed as I, lost in my yarn thoughts, rambled on there by the ski lodge fireplace.

“Just remember: The pattern and the yarn weight should match. The rest you’ll figure out as you go,” I said, slipping a skein of sock yarn out of my bag and into her hand. “Ohhh,” she murmured, touching it. “It’s so skinny!” She pinched out a strand and we laughed.

What You Need to Know: Matching Yarns and Patterns

• Yarns come in different thicknesses.
• Needles come in different thicknesses.
• Patterns call for specific yarn and needle thicknesses.
• When the yarn, the needles, and the pattern match, your project comes out the right size and looks and feels good.
• When they don’t match, your project might turn out the wrong size or look and feel unpleasing.
• The art of choosing a yarn for your project is called yarn substitution, and it’s easy with a few tricks.

How to Pick a Yarn for Your Pattern

1. Get your pattern and a pen.

2. You’re looking for four things in the pattern:

• Yarn-weight number
• Needle size
• Stitches per 4″
• Gauge stitch pattern

3. In the yarn section of the pattern, is there a yarn ball icon with a number in it?

• If yes: The number in the icon is the yarn-weight number; write it down and proceed to Step 5.
• If no: Proceed to Step 4.

4. To figure out yarn weight, look up the yarn on the yarn company’s website and see what it recommends for the gauge. Compare that to the CYC yarn-weight chart below to see what number the pattern matches.

5. You are trying to find a yarn with the same yarn-weight number as your pattern. Many yarn companies print the yarn-ball icon on the label; look for a yarn with the same number and roughly the same fiber content as the yarn suggested in the pattern. If the yarn you’re considering doesn’t have the yarn ball icon on the label, look at the suggested gauge and find something that’s close to the gauge listed in the chart.

6. Once you’ve found a yarn that is the same number as your pattern, you need to swatch. Buy some yarn for this step.

7. Knit your swatch. Cast on enough stitches to make a 6″ square using the needle size that is called for in the pattern; in this example, that would be about 29 stitches. Round up if you need to; the exact stitch count isn’t important as long as your swatch ends up at least 6″ wide. Work in the pattern stitch given for the gauge. If the gauge section doesn’t list a stitch pattern, swatch in stockinette stitch.

8. Keep working on your swatch until it measures 6″ from the bottom.

9. Loosely bind off the stitches and lay the swatch flat.

10. Block your swatch. Soak it in lukewarm water and gently squish out the water, then lay it flat to dry.

11. Once the swatch is dry, measure from side to side with a tape measure: How many stitches are there in a 4″ space?

12. Measure two more times and take the average.

13. Does your stitch gauge match the pattern? Do you like the way the knitting looks and feels? (It’s technically possible to get gauge with a variety of yarn weights. However, it may mean that your sweater will be floppy and open like a fishing net or as stiff as cardboard.) If not, swatch again with a different needle size and reassess.

Resources for Understanding and Picking Yarn

• https://www.craftyarncouncil.com/standards/yarn-weight-system
• https://www.interweave.com/article/knitting/knit-swatch-swatching-smarter/

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