Special thanks to Mark Rougeux for this knitting tutorial.
An article I wrote in July, 2014  prompted a reader to ask about decreasing using circular needles. Nicole Vieu wrote, “I would love a tutorial on using double pointed needles or magic loop for making a hat! I can knit in the round but I have been hesitant to make a hat in the round because of the decrease, I usually make them flat and stitch them together!”
Nicole inspired me to write this particular article. I hope it helps explain things.
Knitting a hat in the round is simple. The decreases are just as easy in the round as they are on a flat piece of knitting. When you get to the top of the crown, just remember you will either need to switch to DPNs, or get a set of circular needles (magic loop ) with a longer cord. My mantra: The smaller the round, the longer the cord. I begin my CO with a 16″ cord and that serves me well for most of the hat. When I start decreasing I switch to a circular needle with at least a 32″ cord.
To switch to a longer cord, simply use the needle from your new cord and begin knitting as usual from the shorter one. Once you knit all the way around, you will have knitted off the 16” circular needle and now your knitting is completely on the longer needle.
What I do next is divide my work in half. I reach between the two stitches at the halfway point and pull a loop of the cord out. You’ll notice in the photo below, I have markers every 30 stitches. My pattern calls for 120 stitches using a #US5 needle. I will decrease four stitches in each round using ssk (slip, slip, knit) after each marker.
The cord is floppy but it really does make it easy to continue decreasing.
The next photo shows the decreasing in progress. The decreases appear very neat and tailored. A little trick I do after each ssk is I give the next two stitches a little tug to tighten the loops. Otherwise, you may have a sloppier decrease edge. With the markers in place and, in this case, a purl stitch immediately after, there is just a tiny bit of extra yarn there. That can create some gaps or holes in your knitting. So, a little tug helps.
Some people opt for DPNs to do their decreases because they don’t understand that circular needles can work very well down to just a few stitches. If you do start using DPNs here, this is what it would look like. I prefer the gentle curves of the cord on the circulars to the points on DPNs. Both do the same thing.
This next photo shows only 8 stitches remaining after the last decrease.
At this point simple snip your yarn leaving about an 8” tail. With a darning needle slip each stitch off as if to purl. Then run the yarn down through the center of the hat, turn the hat inside out, and finish by weaving in the yarn as you normally would.
The finished design of this hat turned out well. The decreases weren’t stressed because I gave each that little tug.
A nod goes out to my son Nicholas for the use of his head in the last photo, and a special thanks to Melissa LaBarre. Her Icehouse Hat can be found on Ravelry here . The pattern is free and elegantly written.
Is there a specific knitting technique you would like to see explained on the blog?