Help with Changing a pattern size

I need help changing the size of a sweater pattern - I knitted the sweater for myself, then my mother saw it and would like me to make her one, but I used the instructions for the largest size on the pattern, and my mother needs a larger size. I've been knitting for a couple of years now, but I can only work from a pattern and am not nearly advanced enough to come up with my own patterns or ad lib with an existing pattern. If I have her measurements, how do I go about adjusting the pattern?

Sometimes you can get the numbers algebraically by figuring out how many stitches/rows the pattern increases by each size. (A calculator helps!)

However, if the sweater is tricky, or has a complicated pattern, you might try googling "adjusting knitting patterns" or some such phrase. I've found a lot of help on line for that type of thing.

Own any of Debbie Stoller's knitting books (Stitch and Bitch etc.)? There's some such advice in them - well, in Stitch and Bitch Nation, certainly - that would probably be helpful. I haven't had occasion to put it into use, but it's worth looking into.

scaifea, I have successfully used the algebraic method but just to make a pattern work with different yarn.

It is tricky when adjusting an overall pattern because we all carry our weight in different places. If you have done the algebra to figure out the # of stitches per inch I would get some measurements from your Mom. and just mark them on paper next to the finished measurements of your sweater. (I'd use bust, waist, arm length, hip and neck to hem or use measurements of a sweater that fits her well.) For example the arm length and width of you sweater might be fine on her but she may need more room someplace else in the sweater design.

Then look at the pattern and look for natural places to add increases and deacreases to get the right number of inches for your Mom. Then I'd just write the number of stitches into the pattern (where ever it gives you a stitch count- # cast on 20th row there should be 242 stitches etc etc.) throughout before you even start knitting- that way you won't get confused throughout.

Be sure you figure in areas you may need for seams if it isn't on circular needles.

Good luck!

This pattern is fairly simple - it's a loose-fitting cardigan with straight edges all around - so I think I'll try the algebra trick (or have my husband the physicist do it for me, since I'm math-impaired). And I've been looking for an excuse to buy more knitting books, so I'll definitely pick up the Stoller books too. Thanks so much for all the help, everyone!