The cuff of a sock has to be loose and stretchy enough to fit over your heel as you’re pulling it on. The standard bind-off most of us learn is pretty firm, to put it mildly. The knit two, slip the right stitch over the left, knit one, slip the right stitch over the left, etc. will give you a very sturdy bind-off without much stretch. It’s terrible for toe-up socks.
I did a little hunting around online and found several recommendations for toe-up socks. The elastic bind-off turned out to be my favorite. The biggest reason why I like it? It’s simple. I’ve tried so many bind-offs that have a zillion steps in the process (I exaggerate, but only by a little). When I read the end of a sock, I am tired and ready to be done. I do not need a complicated process waiting for me before I can finish.
The elastic bind-off is very simple. Here’s all you need to do: 1. Knit two stitches. 2. Slip the left needle into the front of those two stitches. 3. Knit the two stitches together through the back loop. 4. Knit a stitch. 5. Repeat steps 2-4 until you finish. When I’m binding off a sock and get to the last stitch, I like to pick up one extra stitch at the beginning of the round to draw everything together. Then I bind off that extra stitch with the remaining stitch, break the yarn, and draw it through the final stitch.
I use this bind-off for all of my fingerless mitts, and I like the amount of stretch it gives. I find, though, that it’s a little more fiddly than the elastic bind-off, which might not be something you’re interested in after finishing a sock (in the same way many people don’t like to graft a toe).