What a slip stitch does and when you need it
A slip stitch is a seaming technique that closes a gap between two pieces of knitting—or closes a gap in a single piece—by threading yarn through the loops on the edges and pulling them together from the inside. The result is an invisible seam that looks like a continuation of the knit fabric itself, not a visible line of stitches running down the side. You use it most often to close the sides of a sweater after you've knitted the front and back as separate pieces, to seal the opening of a stuffed toy or pillow, or to join the edges of a folded piece of fabric.
The slip stitch is invisible because you're not creating new stitches on top of the fabric—you're using the existing loops at the edges and cinching them closed from inside. This makes it the standard finish for seams that will show, especially on the visible sides of garments. It takes a little practice to keep the tension even, but once you understand the path the needle takes, the motion becomes automatic.
Key Takeaways
- A slip stitch closes seams invisibly by threading yarn through the loops at the edges of your knitted pieces and pulling them together from inside the fabric.
- You need a tapestry needle (also called a yarn needle), the yarn you knitted with, and two pieces of knitting with finished edges ready to join.
- The needle travels in a consistent pattern: up through one side, across to the other side, and back, creating a zigzag path that pulls the edges together.
- Tension matters—pull the yarn snug enough to close the gap but not so tight that the seam puckers or the fabric bunches.
- Practice on a scrap project first so you can feel the rhythm before seaming a finished garment.
What you need before you start
Gather a tapestry needle (a blunt needle with a large eye, designed for yarn), the same yarn you used to knit the pieces, and the two pieces of knitting you want to join. The edges should be finished—meaning you've bound off or otherwise secured the stitches so they won't unravel. If you're seaming the sides of a sweater, you'll be working with the side edges, which are the rows running vertically along the piece.
Cut a length of yarn roughly 3 to 4 times the length of the seam you're closing. This gives you enough yarn to work without running out mid-seam, but not so much that you're wrestling with a tangled tail. Thread the tapestry needle and you're ready to begin.
The basic slip stitch seaming motion
Lay the two pieces flat on a table with the edges you want to join facing up and positioned next to each other, as close as they can be without overlapping. The right sides of the fabric should face you. Insert the needle from the back (the inside) through the first stitch loop on one edge, coming out toward you. This anchors your yarn.
Now the pattern begins: insert the needle into the opposite piece, going in from the front and coming out through the next stitch loop up. Then go back to the first piece, skip one stitch loop (or go into the same loop you just exited—this varies slightly by pattern), and come back out through the next loop. The needle travels in a zigzag: in one side, across to the other, back across to the first, and so on.
As you work, the yarn stays inside the fold between the two pieces. Every few stitches, gently pull the working yarn to tighten the seam and close the gap. The edges will draw together and the seam will disappear into the fabric. Keep the tension even—too loose and the seam won't hold; too tight and the fabric will pucker.
Working stitch by stitch along the seam
The exact path depends on the edge you're seaming. If you're joining two side edges (the vertical edges of a piece), you'll be working into the bumps or loops created by the edge stitches. Insert the needle under the bump closest to the edge, not through the very last stitch of the row. This keeps the seam from being visible on the front of the fabric.
Work your way up the seam, alternating sides with each pass. After every 3 to 5 stitches, pull the yarn snug to close the gap a little more. This prevents you from pulling too hard all at once, which can bunch the fabric. The seam should close gradually and evenly as you move up.
If you're seaming a bound-off edge (like closing the top of a stuffed toy), the motion is similar but you'll be working into the loops of the bound-off stitches themselves. The principle is the same: thread through one side, across to the other, back to the first, and pull gently to close.
Keeping tension even so the seam lies flat
Uneven tension is the most common problem when learning to slip stitch. If you pull too hard on some stitches and not others, the seam will look wavy or the fabric around it will bunch. The solution is to pull the yarn with the same pressure every time, and to do it frequently rather than all at once.
A helpful rhythm: work 3 or 4 stitches, then stop and gently pull the yarn to close that small section. Repeat. This distributes the tension across the whole seam instead of concentrating it in one spot. As you practice, you'll develop a feel for how much pull closes the gap without distorting the fabric.
If you notice the seam is puckering, you've pulled too tight. Loosen it slightly by easing some yarn back out. If the gap isn't closing, you're pulling too gently—increase the tension gradually until the edges meet.
Finishing the seam and securing the yarn
Once you've seamed the entire length, bring the needle to the inside of the fabric one last time. Make a small loop with the working yarn, insert the needle through it, and pull tight to create a knot. Weave the remaining yarn tail through a few stitches on the inside of the seam to hide it, then trim the excess. The knot and tail will be hidden inside the fabric and won't be visible from the outside.
Step back and look at your seam from the front. It should be nearly invisible—the fabric should look like one continuous piece with no visible line of stitches running down the side. If you see a line, you may have been working too close to the edge or pulling unevenly. This is normal on your first attempts; the seam will look better as you practice.
Common mistakes and how to avoid them
The most frequent error is working into the very last stitch of each row instead of the bump just inside it. This makes the seam visible on the front of the fabric. Stay one stitch in from the edge and your seam will disappear.
Another common issue is pulling the yarn too tight too soon. This bunches the fabric and makes the seam look lumpy. Instead, pull gently and frequently. The seam should close gradually as you work your way up.
If you run out of yarn before reaching the end of the seam, weave in the tail, anchor a new length of yarn inside the fabric, and continue. The join will be hidden inside the seam.
Frequently Asked Questions
Can I use a different yarn color for the slip stitch?
You can, but it will be visible because the seam isn't truly invisible—it's just hidden inside the fold. For the most seamless look, use the same yarn you knitted with. If you must use a different color, match it as closely as possible to the fabric.
What if my edges are curling or uneven?
Curled edges make slip stitching harder because the loops aren't clearly defined. Block your pieces before seaming—wet them, pin them to shape, and let them dry. This evens out the edges and makes the seam much easier to work.
How tight should I pull the yarn?
Pull just enough to close the gap between the two pieces. If the fabric around the seam starts to bunch or pucker, you're pulling too hard. The seam should feel snug but the fabric should lie flat.
Do I have to use a tapestry needle?
A tapestry needle is designed for this work because it's blunt and won't split the yarn. A sharp needle can catch and break the fibers. A tapestry needle makes the work faster and the result cleaner.
Can I slip stitch on the inside of a garment instead of the outside?
Yes, if you're seaming an edge that won't show—like the inside seam of a sleeve. The technique is the same, but you'll be working from the inside of the fabric instead of the outside.