When you're substituting yarns for a pattern, knitters know that if that pattern calls for a worsted weight yarn, that substituting another worsted weight yarn is the thing to do. But all worsted weight yarns are not the same. Some yarns like cotton are inherently heavier than yarn made of angora. But even within the vast area of Worsted Weight Wool, you'll find balls of yarn that will weigh differently.
Why does weight matter?
When you finish your garment, you will either end up with a fairly lightweight sweater or an extremely heavy one. If you're doing a lot of cables which takes more yarn, a sweater knit with a heavy fiber will be even heavier. This affects your shoulder seams, the neckline drop, the sleeve length, and the overall comfort. If you're knitting with lace, a heavy yarn will really widen the openwork and leave you holes bigger than you wanted. Brioche uses almost twice as much yarn as stockinette, so you'll definitely want to minimize the total weight.
In these cases, you'll want to select a yarn that weighs less. This is a yarn that gives you more yards per gram in each ball/hank/skein.
On the other hand, if you're working with a "puffy" stitch pattern that you want to lie flat, a heavier yarn will help pull the garment down and stretch out that pattern to a pleasing texture. If you're working with elongated stitches that only look cool when actually elongated, you don't want a yarn so light that the dropped yarn overs puff out and glob together. You want them stretched out to give the full effect.
In these cases, you'll want to select a yarn that weighs more. This is a yarn that gives you less yards per gram in each ball/hank/skein.
Also think about the size. You can use a heavier yarn with a Woman's XS than you can with a Men's size 5X.
When substituting yarn for a pattern, first figure the weight per yard of the yarn listed in the pattern. Divide the total grams by the total yardage on the ball band to find out how many grams one yard of yarn weighs. This is easier to do in grams than ounces since with ounces you'll end up with a slew of fractions to contend with.
Below is a comparison of WORSTED WEIGHT YARNS, ranked from lightest to heaviest:
As you expect, the cotton blends are the heaviest. But look at the difference in wool! There's a big difference in Brooklyn Tweed Shelter at 0.36 grams per yard compared to Sugar Bush Bold at 0.53 grams per yard. A sweater that uses 1300 yards of yarn will weigh 468 grams with Shelter and 689 grams with Bold. That is a substantial difference that you will notice as soon as you pick up the garment.
Sometimes you want it light, sometimes you want it heavy. But knowing that the weight will have an effect on the finished garment, is an important tidbit to tuck away in your brain.
Before you make your next substitution, think about what you're creating and how you want it to behave. Then grab your phone to do a quick calculation to figure out how much one yard of yarn weighs before purchasing your yarn. When you invest time and money into a hand knitted garment, you want it to turn out the best that it can be. This quick little trick helps to do just that!
Hello! I'm Donna Estin, knitwear designer, certified master knitter and instructor. I enjoy designing artistic knitwear that is comfortable. I specialize in sweaters with a contemporary silhouette.