I made a bunch of these this summer for myself. You can’t have too many washable caps like these if you’re undergoing chemo. I adapted this easy pattern so I could turn out a lot of these in quick succession (see changes below). Then I made some for friends from our chemo transfusion room. Two balls make five hats.

Take it from me--these are cancer-patient tested! The Cotton Ease yarn works great and feels good on your head. I have tried other yarns, but synthetics and wools are too heavy and uncomfortable. I wear these around the house or to the gym. Make one for a friend!

Pattern adaptation:
Size 8 circular needle (16-inch) and DPNs.

Cast on 60 on a number 9 straight needle. K1P1 rib onto circular needle. Easy join: turn around and and start knitting the opposite end, so the circle forms. This is helpful, because you don’t have to knit the first row in the round--much easier.
K1P1 rib for two more rows.
Start knitting in stockinette for about 32 rounds or desired height.
Follow decreases in main pattern until you get to K4 K2 tog. Switch to DPNs. At this point, do not knit around after decrease rows.
i.e., k3 K2 tog around, K2 K2 tog around, K1 K2 tog around, K2 tog around--6 sts remain. Tie off.