pfb

Purl into front and back (pfb) is a knitting increase that creates one new stitch from a single stitch on the needle. You insert the working yarn into the front loop of a stitch, purl it, then purl the same stitch again through its back loop before dropping it off the needle. The result is two purled stitches where one existed.

This is one of several increase methods in hand knitting, alongside kfb (knit front and back), yarn overs, and lifted increases. The pfb is most useful for increases that sit flush against the knit surface, since the two resulting stitches sit side by side without a visible hole or elongated stitch. It works equally well in flat knitting and in the round.

Appearance and placement

A pfb increase creates a visible paired set of purled stitches. Because both loops come from the same original stitch, there is no gap. The increase sits along the purl ridge created by working into both front and back. For this reason pfb is often used for shaping at selvages or along decreasing panels where a clean, closed increase line is desired, rather than the decorative hole of a yarn over.

Tension matters here: if the working yarn is pulled too tightly on the first purl, the back loop may be difficult to access. Many knitters work the first insertion slightly loose to allow the second insertion to sit comfortably. The two resulting stitches should sit at the same tension across the next row.

The terminology follows the pattern of other abbreviations in knitting shorthand. The kfb and pfb pair are mirror images on the knit side versus the purl side, making them useful for instructions that need increases that match their surrounding texture. This is standard notation in patterns from UK and US sources.