Changing yarn weight

I have a question and perhaps someone can help me. I have great pattern for a baby sweater that calls for chunky yarn. The guage is 14 sts. = 4 “ on US10 needles over st. st… The sweater knits up very heavy and I’d like to make it in a lighter weight yarn. Are there any suggestions to be able to use this pattern in a medium weight yarn and still keep the proper gauge?
Thanks so much,

You could do it with medium yarn, still use the 10s (or 9s) but knit a larger size. You wouldn’t get the same gauge, but you would get the right size sweater. Or you could use 2 strands of sport or DK yarn and the 10s and it might get the same gauge.

When you say proper gauge, I guess you mean proper size, because it sounds like you want to change the gauge. The conversion would be: new gauge divided by the old gauge. For instance, if you wanted to use a yarn that knitted to 18 sts = 4" in your swatch, (you must make a swatch with the new yarn), then you would multiply the number of stitches in the pattern by 18/14, or 1.286. So if the pattern said to cast on 50 stitches, you would cast on 64 stitches, which is 50 X 18/14. If there is a stitch pattern you might have to add or subtract a stitch or two to get it to come out right.

For number of rows you can probably use the same conversion rate or just go by how many inches you want.