Remember when you first began to knit, you reached a certain point and realized there were less stitches than you started with. Unaware, you most likely dropped stitches or decreased. Learning to decrease is necessary for knitting garments and for many pattern stitches such as lace.
Decreasing stitches is a method to reduce the number of stitches, narrowing or shaping a piece. For example, decreasing stitches to form an armhole allows room for setting in the sleeve. Decreases are also used in lace knitting to compensate for the yarnovers. There are a variety of methods to decrease, depending on what you are trying to achieve. Most decreases have a right or left slant. You might want to work a left slant on the right hand side of a piece, and a right slant on the left hand side to emphasize the slope. By placing the decreases a few stitches from the edge forms a decorative detail, called fashion marks or fully fashioned marks, visible on the right side. The cardigan below shows these marks along the front borders.
Most decreases are worked on the right side of the knitting, but sometimes the wrong side requires decreasing. For example, the pattern instructions might say to decrease stitches on every row. Usually one or two stitches are decreased at a time. I’m not a fan of decreasing more than two stitches at a time when shaping waist areas, armholes, or sleeve caps. I find the fabric pulls in creating a bumpy or slightly puckered look. Most of the time I place decreases one or more stitches from the edge to avoid uneven edges, making the pieces easier to sew together.
Basic Decreases (dec)
Working Two Stitches Together (K2tog or P2tog)
This is the simplest decrease and can be done right at the edge or within a few stitches from the edge. Decreasing the two edge stitches makes the edges uneven, but the decrease isn’t seen when the pieces are sewn together.
Knit two together (K2 tog): Insert your right hand needle into the next two stitches on the left needle knitwise. Knit these two stitches together as one stitch. Knitting two stitches together creates a right slant on the right side of the knitting. A left slant is made by knitting two together through the back loop (k2 tog tbl)
Purl two together (P2 tog): Insert the right needle into the front loops of the next two stitches on left needle purlwise. Then purl these two stitches together as one stitch. Purling two stitches together also creates a right slant on the right side of the knitting. A left slant is created by purling two together through back loop (p2 tog tbl).
The following two decorative decrease techniques are commonly used.
Slip, slip, knit (ssk)
This decrease slants to the left on the knit side or right side of the work. Slip two stitches knitwise one at a time from the left needle to the right needle. Insert the left needle into the fronts of the two slipped stitches on the right needle from left to right, and knit them together by wrapping the yarn around and pulling the loop through to the front, dropping the two slipped stitches.
A left slant appearing on the knit side can be made with purl stitches on the wrong side. Slip two stitches knitwise, one at a time from the left needle to right needle. Return these two stitches to the left needle, leaving them twisted. Purl these stitches together through the back loop.
Slip, knit, pass slipped stitch over (skp) (also sl1,k1,psso or sl1,p1,psso)
This method of decreasing also slants to the left on the knit side. Slip one stitch knitwise. Knit the next stitch. Insert the left needle into the front of the slipped stitch and lift this stitch over the stitch just knitted (psso) – pass the slipped stitch over the knit stitch and off the needle. On a purl row, the instructions would read “sl 1, p1, psso”. You are purling one stitch instead of knitting.
The above are all single decreases and the most common. There are double decreases that I won’t describe here. They are worked very much like the single decreases, and once you master the basic ones they will be easy to knit. Most pattern instructions describe the decreases used in them.
Note on Slipping Stitches: Slipping a stitch is simply passing it from the left needle to right needle. When slipping a stitch knitwise, the stitch twists, but slipped purlwise, the stitch remains untwisted. If the pattern instructions do not specify which way to slip, then slip purlwise, except when decreasing stitches then slip knitwise. To slip knitwise, insert the right needle into the stitch as if to knit and slide it onto the right needle. To slip purlwise, insert the right needle into the stitch as if to purl and slide it onto the right needle.