A step by step tutorial on the central double increase (CDI) and how to improve it so the holes are less visible
Does your knitting pattern ask for a centered double increase? But you have no idea how to knit it? Well then, in this tutorial, I’m going to show yous step by step how to do a centered double increase you can use in the middle of shawls or advanced lace patterns.
And the best part: I am not only going to show you one way to do it, but also a couple of very helpful variations so you can make the holes smaller (for more variations, also check my ultimate list of knitting increases)
ⓘ In knitting patterns, you’ll often find the abbreviations CDI for Centered Double Increase. Sometimes it also says INCTO3 (increase to 3 stitches). This usually does not refer to a specific technique, but rather just a double increase that is centered (as opposed to leaning to the left or the right).
So, let’s dive right into it.
The Standard Central double increase
Step 1: Knit into the back loop of a stitch. But don’t drop the stitch as normal. Keep it on your needles.
Step 2: Knit into the front loop of the same stitch, and keep it on the needle.
Step 3: Identify the little strand between the two stitches you just created and lift it onto your left needle (using the left needle from back to front).
Step 4: Knit that extra loop through the back loop.
And that’s basically it. Like I said, it boils down to a combination of a KBF and a lifted increase.
CENTERED DOUBLE INCREASE VARIATION #1
For a neater version of the standard double increase with smaller holes, you should start with a KFB (Knit front back) instead of a KBF (Knit Back front) and then just knit the lifted increase.
Step 1: Knit into the front loop.
Step 2: Knit into the back loop.
Step 3: Pick up the loop between those two stitches from behind again (will be a bit harder to find).
Step 4: Knit it through the front loop.
This version is a bit harder to work, mainly because knitting a lifted loop through the back loop requires a sharp-pointed needle. But I think it is worth it.
Central double increase Variation #2
For a different look and feel, you can also combine two backward loop increases around one central knit stitch. It’s actually the easier way to knit it, but it runs of creating a sort of laddering effect. On the plus side, it doesn’t shorten any strands between stitches, so it doesn’t pucker the fabric and looks very symmetrical.
Step 1: Knit up to the stitch that will be the center of your increase.
Step 2: Wrap the working yarn around your thumb counter-clockwise.
Step 3: And pick up the loop you created with the right needle from above/behind and pull tight.
Step 4: Knit one stitch (this one is going to be the center of the increase).
Step 5: Wrap the working yarn around your thumb clockwise.
Step 6: Pick up the loop you created from below and pull tight.
Note: If you want to close the somewhat loose loops of this central double increase variation, then you’d have to purl the two stitches to the left and the right through the back loop. This, however, will create visibly twisted stitches, so you have to decide between two evils, sort of.
Centered Double Increase Variation #3
If you would like a denser fabric with less holes, then you’ll have to knit a KLL and KRL into the same stitch. This will shorten the stitches quite a bit. So, actually I am not sure if it’s the best double increase to use every second row. If your pattern requires double increases every 4 or more rows, then this probably would be my favorite version.
Step 1: Knit up to the stitch you want as the center of your double increase and knit a KRL (Knit Right Loop)
Step 2: Knit the next stitch.
Step 3: Knit a KLL (Knit Left Loop).
I personally rather like the look of this increase, though it would not be my favorite for the middle of a shawl as, as I said, it does shorten those stitches quite a bit in the middle.
M2 Left and Right
A very fun variation of the centered double increase is based on the classic Make Two (M2). While this alternative does indeed create quite big holes, that doesn’t mean it’s less beautiful. It depends on the context. For some lace patterns, this could actually be a neater option. I would like to point out, however, that this is, strictly speaking, no central double increase because you need two stitches, while the classic version works with one stitch.
Step 1: Pick up the strands between two stitches.
Step 2: Now knit a regular M1L by knitting that loop through the backloop, but don’t knit the next stitch yet.
Step 2: Instead, pick up the same strand one more time, and now knit the strand through the front loop instead!
This creates a very centered double increase with a beautiful eyelet and very harmonic stitches to either side.
Comparing the 5 alternatives to knit a Central double increase
To finish this already quite a long blog post, I thought it would be nice to compare all these alternatives side by side. As always, I don’t think there is an absolute best and worst technique knitting. Depending on the circumstances and you may want to use one or the other.
I personally like the backward loop variation a lot – especially as it does not shorten the fabric at all. Knitting a central double increase with a KLL/KRL also has it’s charm while I believe that using a M1L and M1R into the strand between two stitches creates the most stunning pattern. Still, this article is meant to present you with options, and you are free to pick your favorite!