Circular knitting needles are two knitting needles without end caps that are joined together with a cord. It allows you to knit "in the round," without switching from one needle to another. Knitting on circular needles may seem a little daunting at first, but because you don't need to join your seams at the end of the project, it will save you time and looks professional. Knitting a hat in the round is both a simple and easy way to knit a hat and to learn how to knit with circular needles. This article is not a basic how-to about knitting techniques and terms. For beginners, refer to beginning knitter's tutorials online (see additional resources).
Choose your yarn. The thicker the yarn, the wider the stitches and the less time it will take you to knit the hat.
Choose your needles. The bigger the needles, the faster the knitting. You also need to decide on the length of cord between the needles. The length of the circular needles always include the length of the cord, so 16 inch circular needles are 16 inches long from the end of the first needle, through the cord, to the end of the other needle. As a rule, you want the length of the needles to be less than the diameter of the hat you are going to knit. It is possible to knit a hat with a longer cord, but it is more difficult. This article will use size 15, 16-inch circular needles.
Create a yarn ball from your skein of yarn.
Make a slip-knot in one end of the yarn. Cast on 48 stitches. Place a plastic knitting marker on the needle after this last stitch.
Join the stitches, this is where knitting in the round differs from typical knitting. Make sure all the stitches in the row are facing down (i.e. the bumps are below the needle). Bring the yarn to the front of your work. Slip the first stitch you cast on from the left needle to the right needle. Take the yarn to the back of your work. Slip the stitch back onto the right-hand needle. You won't have to take this step again, now that you have joined the stitches, when you reach the end of the row just continue knitting normally.
Knit until you reach the marker, then slip the marker from one needle to the next and continue knitting the next row. Because you are knitting in the round, you don't need to knit then purl for a consistent pattern, just knit each row. Continue to knit evenly at 48 stitches per row for about 8 inches.
Start to decrease your stitches in the following pattern: Knit 6 rows, K2tog - repeat this 6 times (36 rows) Knit 5 rows, K2tog - repeat this 6 times (30 rows) Knit 4, K2tog, repeat 6 times Knit 3, K2tog, repeat 6 times Knit 2 K2tog, repeat 6 times Knit 1 K2tog, repeat 6 times K2tog across the whole row. This should leave you with six stitches.
Cut the yarn leaving about 10-12 inches of yarn as a tail. With a yarn needle, thread the tail through the last six stitches. Pull the tail until it draws the yarn together into a single point. Double-knot the yarn. Cut the last bit of tail yarn and that's it, turn the hat inside out and you're all done.