What a Psso Is and Why You Need It

Psso stands for "pass slipped stitch over" and it is a decrease that removes one stitch from your needle by pulling a knit stitch over a slipped stitch. You use it to shape garments, create stitch patterns, and control the width of your work. It appears in nearly every knitting pattern that involves shaping — cardigans, sweaters, hats, and lace designs all rely on it.

The psso decrease leans to the left on your finished fabric, which matters when you are trying to match decreases on both sides of a garment. If you pair a psso on the left side with a knit-two-together (k2tog) on the right side, the decreases mirror each other and your shaping looks intentional rather than accidental.

You will see psso written in patterns as "sl 1, k1, psso" or sometimes shortened to "sk" (slip, knit, pass slipped stitch over). Some modern patterns use "ssk" (slip, slip, knit) instead, which creates the same visual result but uses a different method. Both are correct — the choice depends on your pattern and personal preference.

Key Takeaways

  • Psso is a left-leaning decrease made by slipping a stitch, knitting the next stitch, then pulling the slipped stitch over the knit stitch.
  • The stitch leans left, so pair it with k2tog (which leans right) for balanced shaping on both sides of a garment.
  • You slip the stitch knitwise, knit one, then use your left needle to lift the slipped stitch over the knit stitch and off the needle.
  • Psso and ssk create the same visual result but use different hand movements — choose whichever feels more natural to you.
  • Practice the motion slowly on a swatch before working it into a pattern so the tension stays even.

Step-by-Step: How to Work a Psso

Start with stitches on your left needle and your working yarn in the back. Insert your right needle into the first stitch on your left needle as if you were going to knit it, but instead of knitting, slip the stitch onto your right needle. The stitch moves from left needle to right needle without being worked. This is your slipped stitch.

Now knit the next stitch normally. Insert your right needle through it from left to right, wrap your yarn, and pull the new loop through. You now have two stitches on your right needle: the slipped stitch and the newly knit stitch.

Pick up your left needle and insert the tip under the slipped stitch (the first stitch on your right needle). Lift it up and over the knit stitch and off the needle entirely. You have now passed the slipped stitch over the knit stitch. One stitch remains on your right needle — this is your decrease.

The whole motion takes about three seconds once you have done it a few times. The key is keeping your tension even so the decreased stitch does not look loose or tight compared to the stitches around it.

Psso Versus Ssk: When to Use Each

Both psso and ssk remove one stitch and create a left-leaning decrease, but they use different hand movements. Psso requires you to slip a stitch, knit one, then pass the slipped stitch over. Ssk requires you to slip two stitches knitwise (one at a time), then insert your left needle through both from the left and knit them together.

Psso is older and appears in many vintage patterns. Ssk is more common in modern patterns because many knitters find it faster and easier to control tension. Both produce the same result on the finished fabric, so the choice comes down to which motion feels smoother in your hands.

If your pattern calls for psso and you prefer ssk, you can substitute it without changing how the garment looks. The reverse is also true. Some knitters use psso on the left side of a garment and ssk on the right side straightforward because they find one easier to execute than the other.

Pairing Psso with K2tog for Balanced Shaping

A psso leans left because the slipped stitch ends up on top of the knit stitch. A k2tog (knit two together) leans right because you knit two stitches as one, and the first stitch naturally sits on top. When you want to decrease on both sides of a neckline, armhole, or center panel, use psso on the left side and k2tog on the right side.

For example, if you are shaping a V-neckline, you might work: knit to 3 stitches before the center, psso, knit 1, knit the center stitch, knit 1, k2tog, knit to the end. The two decreases mirror each other and the shaping looks professional.

If you use k2tog on both sides, the decreases will not match and the neckline will look lopsided. If you use psso on both sides, the same problem occurs. Mixing them is what creates the balanced look that separates intentional shaping from accidental mistakes.

Common Mistakes and How to Fix Them

The most common error is slipping the stitch purlwise instead of knitwise. When you slip purlwise, the stitch twists on your needle and the decrease looks uneven. Always slip knitwise for psso — insert your needle as if you were going to knit, then slip without working the stitch.

Another mistake is pulling the slipped stitch over too loosely. If you do not pull it snug as it goes over the knit stitch, the decrease will look loose and the stitches around it will look too tight by comparison. Pull firmly but not so hard that you distort the knit stitch underneath.

Some knitters accidentally knit the slipped stitch instead of slipping it, which means they have not decreased at all — they have just added an extra step. If your stitch count is not dropping where it should, check that you are actually slipping the first stitch and not knitting it.

If your psso stitches look consistently tighter than the rest of your work, you may be pulling too hard on the working yarn after the decrease. Try loosening your tension slightly and see if the stitches even out.

Practice Exercises on a Swatch

Before you work psso into a real project, spend 10 to 15 minutes practicing on a small swatch using yarn and needles you do not mind using for practice. Cast on 20 stitches and knit a few rows in garter stitch (knit every row) to warm up.

On the next row, knit 5 stitches, then work a psso (slip 1, knit 1, psso), knit 5 more stitches, work another psso, knit to the end. Knit the next row plain. Repeat this pattern for 10 rows so you work the decrease multiple times and get a feel for the rhythm.

Look at your swatch from the right side (the side that faces out on a finished garment). The decreased stitches should form a neat diagonal line leaning to the left. If they look uneven, loose, or twisted, adjust your tension or your slip technique and try again on the next row.

Reading Psso in Patterns

Patterns abbreviate psso in different ways depending on the designer. The most common abbreviations are "psso", "pass sl st over", "sl 1, k1, psso", and sometimes just "sk" (which stands for "skip" and means the same thing). Some patterns write out the full instruction: "slip 1 stitch, knit 1, pass slipped stitch over."

If you see "ssk" in a pattern, that is a different decrease that leans the same direction but uses a different method. You can substitute ssk for psso if you prefer, or vice versa. The finished fabric will look the same.

Always check the abbreviation key at the beginning of your pattern to confirm what each abbreviation means, because some designers use their own shorthand. If you cannot find the abbreviation defined, a quick search for the abbreviation plus the word "knitting" will usually show you what it means.

Frequently Asked Questions

Can I use psso on every decrease, or do I have to mix it with k2tog?

You can use psso for every decrease if you want, but your shaping will lean consistently to the left and may look unbalanced on garments with decreases on both sides. Mixing psso and k2tog creates symmetrical shaping that looks more polished. For lace patterns or stitch patterns where the lean direction is part of the design, using the same decrease throughout is correct.

What is the difference between psso and ssk?

Both create a left-leaning decrease, but psso uses slip-knit-pass-over, while ssk uses slip-slip-knit. Ssk is often easier to tension evenly because you are knitting the stitches together rather than passing one over. Many modern patterns use ssk instead of psso, but they produce the same result on the finished fabric.

Why does my psso look loose compared to the rest of my knitting?

Tension is usually the culprit. Try pulling the working yarn a bit tighter after you pass the slipped stitch over, or loosen your overall tension slightly if the decrease is pulling the surrounding stitches too tight. Practice on a swatch to find the tension that matches your regular knitting.

Do I slip the stitch knitwise or purlwise?

Always slip knitwise for psso — insert your needle as if you were going to knit, then slip without working the stitch. Slipping purlwise twists the stitch and makes the decrease look uneven.

Can I substitute ssk if my pattern calls for psso?

Yes. Both stitches lean the same direction and create the same visual result. If ssk feels more natural in your hands, use it instead. The finished garment will look the same.