Or: WAH! How much yarn do I buy?!
I’m knitting a sweater for my friend.
The pattern I’m using is from “The Complete Book of Raglan Sweaters” from Leisure Arts. It has these funky fill-in-the-blank patterns. You choose what size sweater you’re going to make (from 6 mo infant up to a 50-inch chest!), and there’s a chart that has a column for each size. You read down that column and copy over the amount of yarn needed, the number of stitches to cast on, the number of decrease rows to do, how many inches to knit the sleeve, etc.
The pattern calls for worsted, 20 sts/4 in, but I can’t find any worsted I really like, and I’m thinkin’ that if I used bulky yarn, I’d be done faster, my friend gets her sweater sooner, and everybody’s happier. In particular, I have my eye on this new Bernat Solo, with a recommended gauge of 12 sts / 4 in. (Trust me, it’s much prettier in person-- it’s a fuzzy tweed with subtle flecks of all different colors.)
I’m almost certain that the pattern is just based on ratios. So, no problemo. I want the finished chest size to be 48 in, so 48 in / 20 sts * 12 sts = 28.8 in, so I follow the pattern for the 29 inch finished size, but work it in the bulky yarn, and voila, I get my 48 in chest.
The thing that’s scaring me a bit is figuring out how much yarn to buy. If I get too little, according to Finagle’s Law, there will be some kind of dye lot catastrophe. Whadaya think? Should I get the number of ounces called for by the 48-inch size? Is that likely to be too much, or too little?
I’m too much of a beginner (just finished my first hat/scarf set, yeah me!) at this to have a *correct * answer, but the worrier in me says to buy the amount listed for worsted. You’ll have extra, sure, but then you can make her a snappy scarf to go with her sweater, and you won’t spend your whole project eyeing your yarn supply and sweating bullets.
You could try using Knitware Sweater Design, which will rewrite the pattern to your gauge, and it will also give you a rough estimate of how much yarn you need. If you measure some of the yarn and then knit it up and enter in how many stitches and rows you got, it will give you a more accurate estimate.
You (generally speaking) need less yardage of bulkier yarn and more yardage of finer yarn. How that relates to weights, I don’t know. (I still have problems with the idea of a 50g ball. To me, that is an utterly useless measurement.)
But, using the elann guide (which seems about right) and the information on the Bernat Solo, it looks like you’ll need about 16 balls (depending on how big of a sweater you’ll be making).
If you can do it (and it’s a full pullover or full cardigan), you could try starting with just one sleeve. That will generally (loose generalization) take about 1/6th of the total yarn you’ll need. If it takes 3 full balls, you’ll need more. If it only takes 1 and a half, you’ve overbought.
As far as modifying the pattern - watch the armholes and the neckline. Most of the sweater will be ratios, but the initial armhole decrease is usually fixed across all sizes, or has smaller than proportionate variations. And with a raglan, the rate of decrease matters, for the armholes and the back. You may need to recalculate that entire section.
You’ll also need to at least think about the drape - to make sure that the yarn you’re using on the needles you’re using hangs the way you want it to, and isn’t too stiff or too holy.