Mattress Stitch: An Invisible Seam for Stockinette Stitch

close-up of woman knitting blue pieces
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The Perfect Choice

The sewing needle is placed under the strand one stitch in from the edge.
The Spruce / Sarah E. White

The mattress stitch is a great way to vertically connect two pieces of stockinette stitch fabric so it looks seamless. It's a perfect technique for sewing sweater seams, blanket squares, and any other seams that you want to disappear in the finished project.

This is an easy stitch that every level of knitter can do and it's one of the quickest ways to sew up a seam. By the time you're done, only you will know where the seam is and even then, you will have to feel for it within the fabric. 

For illustration, different colored swatches are used in the example photographs. 

Begin the Stitch

The mattress stitch can be worked either a half stitch or a whole stitch in from the edge of the knitting. It's much easier to sew a full stitch in so you can avoid working with those messy edge stitches.

  • You can work with the tail left over from casting on or binding off if you like.
  • If you prefer, you can also join in a new piece of yarn, beginning just as you would when weaving in an end. 

To begin, give your knitting a gentle pull between the first row and the second row of knitting. You'll see a series of little bars of yarn running between the stitches. These are what you use to stitch the pieces together.

Slide your sewing needle under the first bar.

Beginning the Seam

Working in the same place on the second piece of knitting.
The Spruce / Sarah E. White

Find the first bar on the second piece of knitting in the same manner as you found it on the first. Once again, work the stitch by going under the bar.

Continue in this manner, alternating sides as you go, until you have worked a few stitches on each side. Pull the yarn gently as you go, but don't worry about making the pieces completely flush.

Fixing a Missed Stitch

The nice thing about the mattress stitch is that it's easy to pull out and rework if you find that you missed a stitch or it's simply not looking the way it should. You will not damage either piece of knitted fabric by backing up a bit.

  1. Remove the needle from the yarn.
  2. Gently separate the two pieces of knit fabric so your seaming yarn has a bit of slack.
  3. Use your needle to pull out the last mattress stitches you made, drawing the entire yarn tail back through the loops.
  4. Continue this until you've reached the problem spot in your seam.
  5. Gently pull the knit stitches on both pieces of fabric so they relax and go back into their original shape before continuing with your mattress stitch.

Tip: Be sure to look back over your seam and inspect it for any missed stitches as you work. It's disappointing to discover a mistake after you've finished the entire seam or, worse yet, after the entire sweater is assembled.

Finishing the Seam

A partial seam worked in mattress stitch
The Spruce / Sarah E. White

Once you've gone through a few stitches, pull the working yarn more tightly and the seam will close up like magic, making the two pieces of knitting look like a continuous piece.

Pull the yarn straight in the direction of the seam you are knitting for best results. Continue in this manner until the whole seam is finished.

When you have worked to the end of the pieces you are seaming together, give the working yarn a final tug. Weave in the end to make sure your seam stays secure.

Tip: Do not pull too tight on the working yarn. You do not want your fabric to bunch up, but to become one solid and flat piece. If you do happen to pull it too tight, gently separate the knit stitches, beginning at the top and working your way down until the seam loosens up.