Your best bet is to knit a swatch larger than 4x4 and then measure the stitches in the center to get a count without the edge. Then, if you have too many stitches per inch, you go up a needle size. Too few per inch, go down a needle size.
Stitch gauge is more important than row gauge--you can always knit a different number of rows, but you can't change the width. Most patterns are written so that you knit for a certain number of inches, anyway.