OK, so! All that’s left once the body and sleeves are separated is to knit three tubes — a body and two sleeves. When you’re ready to work the sleeves, which you can do at any time, you simply put the live stitches onto DPNs (or whatever you prefer), reattach your yarn, and pick up and knit one stitch into each of the underarm cast-on stitches, again marking the center point of the underarm with a marker. You can make the body and sleeves as long or short as you like — from a cap-sleeved crop top to a long-sleeved dress. Totally up to you. Just knit to the desired length, work your ribbing (or whatever), and bind off.
But that leaves the matter of shaping, for which there’s a simple formula. And it applies to all sweaters, so knowing how to do it is also beneficial in modifying a written pattern to suit your own shape.
Let’s consider a sleeve first, since it’s generally only shaped one direction — from larger (at the upper arm) to smaller (at the wrist). You already have your upper-arm measurement from your yoke calculations. (Mine is 12 inches, which at my gauge of 3.5 sts/inch is 42 sts.) Now measure your wrist and adjust for whatever ease you want there. I’d like my sleeve to decrease from 12 inches (42 sts) to 10 inches (35 sts) at the spot where I’ll start my cuff. Now measure the distance between where you want to place your first decrease and your last*, and multiply that number times your row gauge. My sleeve is already pretty slender and my arms are pretty straight down past my elbow, so I’m not going to work the first decrease until I get to my forearm. The distance from my first increase to my last will be only 5 inches; multiply that by my row gauge of 5 rows/inch and and I know I’ve got 25 rounds over which to work my decreases.
Decreases and increases are generally worked in mirrored pairs, one on either side of your marker — e.g., an SSK and a K2tog for decreases; an M1R and M1L for increases. So each decrease round on a sleeve removes 2 stitches. My first sleeve decrease round will take me from 42 stitches to 40. To get from there to 36 (rounding from 35), I’ll only decrease 2 more times (2 sts x 2 rounds = 4 sts decreased). And I have 25 rounds to do that, so I’ll decrease at the 12th and 25th rounds. (If you’re decreasing all the way down your arm — and/or working at a smaller gauge than I am — your equation will have you decreasing more often than that.)
A written pattern with “waist shaping” will assume you have an hourglass figure: The sweater will get smaller (decrease) as it approaches the waist, then larger again (increase) as it heads toward the hips. You may or may not be shaped that way, but you have the power to shape your sweater however you like. The waist shaping formula is exactly the same as above. Whether you’re sloping in or out, you measure the distance between the wider and narrower spots, then multiply that number by your row gauge — that’s how many rows you have to work your increases/decreases. Again, you want to work a mirrored pair of stitches at each marker, so in this case you’re adding or subtracting 4 stitches per round — 2 on each side. Calculate how many stitches you need at the widest point (circumference x stitch gauge), and how many at the narrowest. The difference is how many stitches you need to increase or decrease. Divide the difference by 4, since that’s how many stitches you’ll add/remove per round, and that tells you how many increase/decrease rounds you’ll work. Distribute those evenly between the allotted rounds.
I’m not doing any waist decreasing on this sweater, just knitting straight down from chest to waist, but then I’m increasing a few times so I can maintain my 2-inch ease at the hips. (My hips are a bit wider than my chest.) I’m starting out with 37 inches (130 sts) and want to increase that to about 41 inches (144 sts). We’re dealing with multiples of 4 for body shaping, so let’s say I’ll add 16 stitches (that’s 4 increase rounds), for a total of 146 stitches (130 + 16). And I’ll distribute those 4 increase rounds over a span of about 6 inches (30 rounds). My first increase round will get me from 130 stitches to 134. Three more increase rounds over 30 rounds means one every 10th round. Then I’ll work even until I’m ready to rib and bind off.
That’s all there is to it!
I’ll have some final thoughts for you, once I’ve finished this sweater. Just need to round up some more yarn for it …
*Whatever you do, be sure to keep detailed notes about your first sleeve, since you need to knit an exact replica for the other arm. You’ll want to know how long your sleeve was (from the underarm) when you worked your first decrease, and how often and how far apart you decreased after that, plus total length before you switched to ribbing.
POSTS IN THIS SERIES: [Favorite it on Ravelry]
Introduction / Part 1: Casting on and marking raglans / Part 2: Raglans and neck shaping / Part 3: Finishing the neck and yoke / Part 4: Separating the sleeves and body / Part 5: The art of sweater shaping / Prologue: The possibilities are endless