What KFB Means and When You Use It

KFB stands for "knit front and back," and it is an increase that turns one stitch into two stitches in a single motion. You knit into the front loop of a stitch the normal way, then before dropping it off the needle, you knit into the back loop of that same stitch. This creates two new stitches where one existed before.

You use KFB when a pattern calls for an increase and you want the result to be relatively invisible. Unlike some increases that leave a visible hole or a slant, KFB blends into the fabric because both new stitches come from the same original stitch. It appears most often in shaping—adding stitches for sleeve caps, necklines, or waist shaping in fitted garments.

KFB is one of the easiest increases to learn because it requires no yarn overs, no dropped stitches, and no working into rows below. If you can knit, you can KFB.

Key Takeaways

  • KFB creates two stitches from one by knitting into both the front and back loops of the same stitch without dropping it off the needle.
  • The increase sits flush with the fabric and does not create a visible hole, making it ideal for fitted garments and seamless shaping.
  • You must keep the original stitch on the left needle until you have worked both loops, then slip it off as normal.
  • KFB leans slightly to the right, so if you need a left-leaning increase, you can use KBF (knit back and front) instead.

Step-by-Step Instructions for KFB

Insert your right needle into the front loop of the stitch you want to increase, the same way you would for a normal knit stitch. Wrap the yarn around the needle and pull through to create a new stitch. Do not drop the original stitch off the left needle yet—this is the critical step that many beginners miss.

Now insert your right needle into the back loop of that same stitch, still sitting on the left needle. Wrap the yarn around the needle again and pull through to create a second new stitch. Now you can drop the original stitch off the left needle. You now have two stitches on your right needle where you started with one.

The whole motion takes about three seconds once you have done it a few times. The key is remembering that the original stitch stays on the left needle until both loops have been worked.

Common Mistakes and How to Avoid Them

The most frequent error is dropping the original stitch off the needle after the first loop. If you do this, you will have only one new stitch instead of two, and your increase will not work. Slow down on your first few KFBs and consciously leave the stitch on the needle after the front loop is complete.

Another mistake is working into the wrong loop on the second pass. The back loop is the one that runs away from you on the left needle—it sits behind the front loop. If you accidentally knit into the front loop twice, you will create a twisted stitch on the second pass. Looking at your needle from the side helps: the back loop is clearly visible as a separate strand.

Some knitters accidentally create a yarn over instead of a true increase by wrapping the yarn but not pulling it through properly. Make sure you complete both stitches fully before moving on—each one should sit securely on the right needle.

Where KFB Appears in Patterns

Patterns write KFB as straightforward "KFB" or sometimes "k1f&b" in abbreviated form. It usually appears in a row instruction like "K5, KFB, K5" (knit 5 stitches, increase 1 stitch, knit 5 stitches). When you see it in a pattern, that is the exact spot where you perform the increase.

You will encounter KFB most often in sweater patterns, especially around armholes and necklines where the fabric needs to expand gradually. It also appears in hat patterns that increase from a small cast-on, and in shawls that grow outward from a center point. Some patterns call for multiple KFBs in a single row to create a more dramatic increase.

If a pattern says "KFB across" or "KFB every stitch," you perform the increase on every single stitch in that row, which doubles your stitch count. This is common in patterns that start with very few stitches and need to reach a larger width quickly.

KFB Versus Other Increases

KFB is not the only way to add stitches. A yarn over (YO) creates a hole in the fabric as part of the design—you straightforward wrap the yarn around the needle without knitting a stitch. This is intentional in lace patterns but not suitable for invisible shaping. A make one (M1) increase lifts the strand between two stitches and knits into it, creating an increase that leans left or right depending on which direction you work it.

KFB is faster than M1 because you do not have to pick up a strand between stitches, and it is more invisible than a yarn over. The trade-off is that KFB creates a slight right lean, whereas M1 can be worked to lean either direction. For most garment shaping, KFB is the simplest choice.

If your pattern specifies a particular increase, use that one. If it just says "increase 1 stitch," KFB is a safe default that works in nearly any situation.

Practicing KFB on a Swatch

Before you use KFB in an actual project, practice on a small swatch using yarn and needles in a size you are comfortable with. Cast on 10 stitches and knit 4 rows in stockinette stitch (knit on the right side, purl on the wrong side). On row 5, knit 4 stitches, then KFB, then knit the remaining 5 stitches. You now have 11 stitches.

Knit another 4 rows without increasing. On row 10, knit 4 stitches, KFB, knit 6 stitches. You now have 12 stitches. Continue this pattern—increasing every 5 rows—until you feel confident with the motion. The swatch will show you exactly what the increase looks like in your yarn and help you spot any mistakes before they appear in a finished garment.

Pay attention to how the increased stitch sits in relation to the stitches around it. It should blend in smoothly without twisting or creating a hole. If it looks twisted, you likely worked into the wrong loop on the second pass.

Frequently Asked Questions

What is the difference between KFB and KBF?

KBF (knit back and front) is the same increase worked in reverse order—you knit the back loop first, then the front loop. KBF leans left instead of right. Both create the same two-stitch result, but the lean direction differs. Use KBF on the left side of a garment if you want the increases to slant toward the center.

Can I use KFB on purl rows?

Yes. On a purl row, you would perform PFB (purl front and back) using the exact same logic—purl into the front loop, then the back loop of the same stitch without dropping it. The motion is identical to KFB, just with a purl stitch instead of a knit stitch.

Does KFB create a visible hole?

No, KFB does not create a hole. It is one of the most invisible increases available. If you see a hole at your increase, you likely worked a yarn over by accident instead of knitting into both loops of the stitch.

What if I accidentally drop the stitch before working the back loop?

You will have only one new stitch instead of two. Pick the dropped stitch back up with your needle and work the back loop as planned. If you do not catch it when ready, you may need to ladder it back up from a row or two below, which is more work. This is why slowing down on early KFBs is worth the time.

How do I know which loop is the back loop?

Look at your left needle from the side. The front loop is closest to you; the back loop sits behind it. The back loop is the one that would be on the far side of the needle if you were looking straight down at it. With practice, you will feel the difference without looking.