I made this for my teapot which is a 6 cupper - it ACTUALLY holds 4.5 cups of water - just. It is about 4 inches high and 17 inches around.

The cozy is felted more or less to fit your pot, the stockinette will roll up at the bottom to make a sturdy edge when it is felted. It is easy to make larger or smaller by adding stitches and/or rows or using a larger yarn, or felting it less.

I used about 3/4 of a ball of the Lambs Pride, any felt-able wool will work.