There’s a question I get asked on a regular basis … it has several forms, but in essence it is this: knitter wants to make one of my patterns, which calls for certain weight yarn. They want to use a different weight of yarn. How many yards will they need?
This turns out to be a more complicated question to answer than you might think!
Let’s get concrete here, and take a specific shawl as an example — say, Levade. The pattern-as-written calls for 450-500 yards of fingering-weight yarn. Like many lace shawls, the pattern suggests a needle size (#7) that is several sizes up from what is listed on the yarn label. This is intentional — the goal is to create an open, airy fabric that blocks and drapes beautifully.
Using a Thicker Yarn
Jane Knitter doesn’t have enough fingering-weight yarn in her stash to make this shawl, but she does have some DK and worsted-weight yarn in large enough quantities to make the shawl … or does she? If she uses a #7 needle with a thicker yarn, the fabric won’t have the right characteristics. The thicker the yarn she substitutes, the more firm and dense the fabric will be. If she tries to make the shawl with a #7 needle and 500 yards of worsted-weight yarn, she won’t run out of yarn … but she may create a “shawl” that is much more stiff than she wanted. Try it with a bulky yarn and the shawl may stand up all by itself!
The solution to the too-thick fabric problem is to use a needle that is appropriate for the yarn she has — for DK, I’d go up to a #9, and for worsted-weight, a #10 or even higher. She’ll need to swatch, too, to make sure she likes the fabric she’s getting. Once she’s settled with a needle, she has a new problem … if she makes the shawl as written with a larger needle and thicker yarn, the shawl will be bigger (perhaps MUCH bigger) than the original — and it will use a lot more yarn. There’s no simple way to calculate how much, though a swatch and very accurate scale can help her get an estimate.
If she doesn’t want a bigger shawl, she’ll need to modify the pattern — do fewer rows, somehow. This will use less yarn than making as written … though how much less is (again) difficult to know in advance.
Using a Thinner Yarn
Jack Knitter, on the other hand, has piles of laceweight in his stash — more than he knows what to do with. He’d like to make Levade with some laceweight instead of fingering weight yarn. The good news is, he can probably get away with using laceweight and #7 needles — the resulting fabric will be ephemeral and gauzy, but the shawl will be about the same size as the original and use about the same amount of yarn.
Jack swatches like a good little knitter, but finds he doesn’t like the fabric he’s getting on #7 needles with his laceweight. He has to go down to a #4 before he’s happy. What does this mean for his shawl? If he works the pattern as written with #4’s, he’ll get a tiny little shawl and use up less yarn. This isn’t what he’s going for! The solution is to add rows (often there’s a good place to repeat a portion of a pattern) until it’s the size he wants. Again, the amount of yarn he’ll need is highly variable at this point.
So What Is A Knitter To Do?
If you don’t have the weight yarn that’s called for in a pattern, don’t despair … but don’t expect an easy answer, either! You’ll need to swatch and do some math and maybe alter a pattern to get results you’ll be happy with. Tame that knitting, make it yours!