Every decrease in knitting takes two or three stitches and makes one, and every decrease leans. Some slant to the right, some to the left, and one stands straight up. Pairing them correctly is what makes the shaping on a hat crown, a raglan sleeve or a lace edge look deliberate.
The two basic decreases
Knit two together (k2tog). Insert the right needle through the next two stitches as if to knit, wrap the yarn, and pull through both. The stitch that ends on top is the one on the right, so the slant goes to the right, pointing up and to the right when viewed from the front.
Slip, slip, knit (ssk). Slip the next two stitches one at a time as if to knit. Insert the left needle through the fronts of both and knit them together. The top stitch now is on the left, so the slant goes left.
Because the two lean in opposite directions, a pair is usually used: a k2tog at the right end of a shaping section and an ssk at the left. Hat crowns use both, placed mirror-fashion on either side of each marked section.
Purl side decreases
On a wrong side row, the same lean is reached with different stitches.
- Purl two together (p2tog) gives a right lean on the right side, like k2tog.
- Purl two together through the back loops (p2tog tbl) gives a left lean on the right side, like ssk.
In stockinette, those rows show only the final result on the front, so choose the one that matches the direction you want.
The centred double decrease
Some patterns take away two stitches at once in a vertical line, for lace spines and mitred corners. The central double decrease slips two stitches together as if to knit, knits the next, and passes the two slipped stitches over. The result is a neat stack with the top stitch in the middle. The stitch database includes it along with k2tog, ssk and slip, knit, pass over.
Why the lean matters
A single k2tog in a stockinette field looks like a small ridge going up to the right. A line of them makes a slanted rope. To shape a neck or a raglan with visible decreases, a designer positions the decreases two or three stitches in from the edge, so the lean travels along the seam like a decorative line. This is called full-fashioned shaping. Put the k2tog on the edge that should lean toward the edge.
For a hat crown, decreasing every other round with k2tog alone tilts the spiral toward the right; using ssk at the start and k2tog at the end of each section keeps the lines straight, like the spokes of a wheel. Keep counts in the marker sections, so the decreases are the same in every wedge.
Making ssk neat
A common complaint is that ssk leaves a looser stitch than k2tog. Two fixes: slip the second stitch as if to purl instead of to knit, then return both to the left needle and knit them together through the back loops. This twists both stitches and closes the gap. Or, use a smaller needle for the first stitch.
Choosing for lace
In lace each decrease balances a yarn over. Usually a yarn over comes before a k2tog or after an ssk so that the two make a pair: a stitch is added and a stitch is removed, and the total stays the same. The hole created by the yarn over leans with the decrease next to it, and reversing the pair reverses the lean of the eyelet. Follow the pattern exactly, since an eyelet with the wrong direction of lean changes the shape of the pattern.
Shaping in the round versus flat
In the round, every round is a right-side round, so both lean directions appear as written. Working flat, decreases on the wrong side rows look different from those on the right side rows. Patterns often put all shaping on right-side rows to avoid the mismatch.
Where to put the decreases
| Project | Decrease | Placement |
|---|---|---|
| Hat crown | k2tog, ssk | Two per wedge, start and end |
| Raglan sleeve | k2tog, ssk | Each side of a seam stitch |
| Toe of a sock | k2tog, ssk | Each side of the toe |
| Shawl edge | k2tog, ssk | Two to three stitches in |
| Lace | k2tog, ssk, central double | With yarn overs |
Counting
Each decrease removes one stitch, except the central double decrease, which removes two. Before starting a decrease round, count how many you need and divide by the number of markers, so the total at the end matches the number in brackets. The hat designer in the tools section sets out the crown in rounds with the count for each round, based on head size and gauge.