There are two main methods for fixing a too-wide sweater. The most obvious (although not the most knitterly) method of fixing this is to get yourself to a serger, and simply take out a whack of sweater. This may seem like odd advice, but when you come to realize that many commercial sweaters are in fact serged together from flat-knit sheets or tubes of knitting, it becomes less odd. Here is a link to a sweater "saved by the serger," knit by my friend and fellow-Madisonian, the Ravelry hall-of-famer Rududu. You can see that Rududu narrowed the sleeves on a mohair garment by simply serging them smaller.
For a more knitterly approach, consider reworking the knit fabric. As you know, the same number of stitches in ribbing are substantially narrower than the same number in stockinette, because ribbing "draws up." TECHknitting blog has already shown how to rework stockinette into ribbing in the context of rolling stockinette scarves, and the cure is the same for a too-wide sweater. A panel or two of ribbing in the middle of a stockinette field will narrow the entire garment.
If, on a bottom-up garment, the neckband has already been put on, it must be taken off again, and the same applies to the need to remove the bottom band on a top-down garment. Once the band is off, pick out the cast-off until you have live stitches again, then rework the stockinette into ribbing using a crochet hook to rehook-up the dropped down columns (again, instructions are here). You can make a single panel in the middle of a garment pattern or two panels, with a strip of plain stockinette between, or any arrangement you might like. Work a few columns per panel into ribbing and try the garment on again. Still too wide? Add more columns (or panels!) of ribbing. Of course, you can try on the garment as you rework the fabric into ribbing, so you won't overshoot the mark.
And, naturally, you can tighten up too-loose sleeves by this trick also.
--TK
You have been reading TECHknitting blog on: "fixing a too-wide sweater."
This is the first in a series on garment correction. The others in this series include
Part 2: My sweater is too long, my sweater is too short
Part 3:My sweater is too tight under the arms/at the bust/chest--the magic of gussets
Part 4: My hat is too loose
Part 5: My sweater slips off my shoulders
Part 6 (still to come): My sweater is too small around my middle