Demystifying Yarn Substitution

With the variety of yarns available now, substituting yarn can be confusing—but it doesn't have to be. Make yarn substitution easier with these handy tips.

| November 2014

Lamb's Pride

The structure and fiber content of the yarn you use will affect the look of the finished fabric. This swatch is knit with Lamb's Pride, a wool and mohair singles yarn.

Photo by John Polak

The Knowledgeable Knitter (Storey Publishing, 2014) by Margaret Radcliffe offers an in-depth tour of a sweater-knitting project to show the choices and options open to every knitter at every step. Radcliffe demonstrates not only how to execute these techniques but why you might choose one over another, allowing you to make tailored, elegant items that are beautiful reflections of your personal style.

Finding a Yarn Substitution for Your Pattern

You have the best chance of a successful garment the more closely you match the yarn used in the original design; however, you shouldn’t feel compelled to use the identical yarn. There are almost always appropriate yarns you can substitute. You just need to match the yarn’s three key attributes as closely as possible: these are the thickness of the yarn, the fiber content, and the yarn’s structure and texture. You should also consider the color of the yarn, but that’s more a matter of aesthetics and personal preference.

Understanding Yarn Weights

There are several systems for yarn weights in use. In the United States, the different thicknesses of yarn have traditionally been called by name, such as sport weight, worsted weight, and bulky weight. In the United Kingdom, the terms include 4-ply and DK (“double knitting”). The Craft Yarn Council has tried to standardize references to yarn weight for knitting and crochet using a numbered system that begins with size 0 for the thinnest yarns and ends with size 6 for the thickest. In all of these cases, the label refers to a range of yarns with similar thicknesses that may or may not be close enough to the thickness you want.

To check for a comparable thickness, you need to compare the yards per ounce (or gram or pound). If you are lucky, the pattern will provide yarn specifications that include how many yards or meters are in each ball or skein and how much each ball or skein weighs. Divide the weight by the length for the yarn you’re considering and compare the result to the original yarn. If one provides weight in grams and the other in ounces, you’ll need to convert them to the same units. After decades of doing these conversions, I have memorized that 1.75 ounces equals 50 grams. This is really all you need to remember. Or, if it seems simpler to you, 3.5 ounces equals 100 grams.

For example, the pattern calls for a worsted-weight wool yarn with 110 yards per 50-gram ball. You want to substitute a wool yarn with 198 yards per 100-gram ball. The easiest thing to do is to multiply the yards in the original ball by two to see how many yards would be in a 100-gram ball: 110 yards × 2 = 220 yards. The substitute yarn has only 198 yards in the same weight, so it’s a little thicker or denser than the original. A second yarn you’re considering is packaged with 225 yards in 4 ounces. To compare it to the original, you’ll need to figure out how many yards are in 50 grams. Remember that 1.75 ounces = 50 grams. Divide 4 ounces by 1.75 ounces to discover how many 50-gram balls are in 4 ounces, and you get 2.29. Divide 225 yards by 2.29 to get 98.25 yards in 50 grams, which is also a little thicker or denser than the original (which you’ll remember had 110 yards in a 50-gram ball). Are either of these yarns close enough to substitute? The answer is a solid maybe! You’ll need to test them out by knitting a swatch to see if you like the fabric when you are knitting at the correct gauge, but you also need to consider fiber content and structure, so read on.

When You Don’t Know the Yarn Specs

If your yarn is missing a label or the label doesn’t contain enough information, you can figure out what needle size would be appropriate by this simple test. Fold a strand of the yarn in half and hold it across the holes in a needle gauge. The hole that the double strand covers will indicate the needle size that will serve as a starting point. Knit a swatch with this size to see if you can match the gauge specifications and produce a suitable fabric. Adjust the needle size depending on your results: If you need to get more stitches per inch, use a smaller needle, which will make the fabric tighter and less stretchy; for fewer stitches per inch use a larger needle, which will result in a looser, stretchier fabric.

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