Knit in front and back: stitch structure

One of the first increases that many new knitters encounter is kfb: knitting in the front and back legs of the same stitch. This increase is one solution to the problem of how to knit twice into the same stitch and end up with two stitches instead of an elongated stitch. My goal with this post is to explain the structure of kfb, both how the two resulting stitches are kept separate, and why it makes what looks like a purl blip on the left side of the stitch even though no purl stitch is involved.

This post assumes you are familiar with the concept of adding a half-twist to a single stitch by knitting through the back loop.

All my other stitch structure posts can be found under my stitch structure tag, or in the menu at the top of this page.


  1. These posts aren’t meant as instructions for how to work these stitches; instead I’m showing the structure of the resulting stitches. In aid of that, I am not showing needles in the stitches as I feel they make it harder to see the fabric structure.
  2. The yarn is drawn to be much thinner relative to the stitch size than would be practical for actual knitting. This helps make it easier to see the structure, but it doesn’t look exactly like the final knitting.
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Here is a pair of two existing knit stitches. The pale green top stitch has been formed by pulling a loop through the medium green bottom stitch. If a knitter wants to make two knit stitches in the pale green loop, they need to find a way to somehow anchor the two new stitches separately.

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Knitting through the front leg of the stitch is just another way of saying “knit a normal stitch”, so that first new dark green stitch is shown here, anchored as usual in the light green stitch from the previous row.

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The second half of kfb involves twisting the yarn on the left side of the stitch in the previous row. A loop has been formed by twisting the left side of the light green stitch. This twist is introduced in the process of knitting through the back leg.

Here, a second dark green knit stitch has been pulled through the twisted pale green loop, showing how the pale green stitch has been manipulated to anchor two dark green knit stitches. After knitting, the pale green twisted loop turns and points to the side. The crossed yarn from the twist sits between the two stitches, so that both stitches are held separately in place. The twisted loop makes a bar in front of the second dark green stitch that resembles a purl stitch, even though no purl stitch has been worked.

Personally, I don’t use this increase very often; I like it best in two situations: garter stitch, and in spots where most other increases are really awkward and I don’t want to use yarnovers for whatever reason. (The example that comes to mind is working a top down hat — I might use kfb for the first round of increases, when I’m working with a really tiny number of stitches.)

The question I have is why it’s often taught to beginners. Is it because it’s seen as easier than other increases because it’s all knit stitches and it doesn’t leave a hole?

PS. Using kfb or not is a matter of personal preference — if it works for you, go for it. I admit to not liking it very much.