Hard to say, your gauge double knitting is probably different than not double knitting.
I think I went with the same number of stitches as many hats (I was determined to get a good hat when I was learning how to knit) taught me were right and it came out a little large.
My DK hat doesn't stretch to fit at all, it could handle a stitch or two less. But it's also nice because my head doesn't feel squished after wearing it for a long time.
Originally Posted by klymyshyn
I believe that I've heard that you should make the outer layer only slightly larger so that the inner layer will not pucker.
That seems to be taken care of by the differences in gauge. Except it's my inner layer that comes out slightly larger.
But I can still use the inner layer as the inner layer, it kind of blocks itself right.