Here is another simple hat that will work for any yarn, any gauge, any size.

This is not so much a pattern as a sketch to be adjusted
for size (e.g., width can be less than 4½“ and length
less than 20–21” for a smaller hat). Since the instructions
are based on measurements rather than stitch
counts, any yarn weight and gauge can be used.
It is helpful to mark the right side of the knitting.
The hat shown here is worked with 2-ply yarns, about
DK weight (1,100 ypp, 13 wpi), worked on size 6
(4 mm) needles. There were 25 stitches at 5” wide;
108 stitches were picked up around the top for the
crown. The same number was picked up for the lower
edge, and several rounds of knit 1, purl 1 rib were
worked. Crown decreases were worked in four sections,
with 2 stitches decreased in each section (total
of 8 stitches decreased each decrease round).