Enlarging sweater by blocking - how much?

I committed one of the cardinal sins of knitting: I did not recheck my gauge after the initial gauge test. As a result, the sweater I’m knitting is turning out much smaller. The gauge was supposed to be 14 stitches/20 rows to 4 inches. Mine is 15 stitches/22 rows to 4 inches. The yarn is Noro Kochoran and Plymouth baby alpaca. I would like to know how much bigger I can make it by blocking?
Thanks for the help.

Ouch.
You can stretch the sweater somewhat by blocking, but what you gain in width you will probably lose in length. Or vice versa.

You could certainly knit extra rows to make the sweater longer than planned, then try to block it wider. You will most likely gain only an inch or two, though, and would have to repeat the blocking after each washing.

A better solution comes from “Knitting in Plain English” by Maggie Righetti. Knit two gussets – single strips that are as long as the distance from the bottom of the sweater to the end of the sleeve.
Open the side and sleeve seams and mattress stitch the gussets in place. If you match the rows and pattern stitches, the added strips should be almost invisible. Or you can make them a design feature by letting the new seams show on the outside or adding i-cord to emphasize them. Or use a different stitch altogether. Or a different color.
Good luck – you can save this sweater.

14/20 vs. 15/22= bigger.

HELP!!! my brain is now confoozeled!!!

14/4=3.5 spi, 15/4=3.75 spi…so if you cast on 10 with the first gauge for example, the width will be 10/3.5=2.86 inches. The width for the second with a co of 10 would be 10/3.75=2.67 inches…slightly smaller. The row gauge however 20/4=5
vs 22/4=5.5 the length on the second will be slightly longer.

I just did a pattern with Noro Kureyon (45% silk, kid mohair and wool) and the width stretched substantially with blocking and you’re going to have a little extra length anyway. I think with the small difference you have here it shouldn’t be a problem…especially if you do a wet block.