Mattress Stitch

Mattress Stitch: How to Sew Vertical Seams in Stockinette Stitch

Mattress stitch is a terrific stitch for sewing vertical seams, like the side seams of a sweater. It’s fairly quick and easy to do, and it’s fun to zip it up. (If you’ve never done mattress stitch, you’ll see what I mean in the video. There’s great satisfaction in seeing it come together.)

Mattress stitch is always done with the right side facing. When the seam is done, it is nearly invisible from the right side. Watch this video to see how it’s done:

Mattress Stitch Instructions

  1. Cut your seaming yarn a little more than twice as long as the seam and thread it on a darning needle.
  2. Work between the 1st and 2nd column of stitches on each piece. Using your darning needle, pick up the bar that runs between those columns as follows:
    1. Pick up the 1st bar on one piece, leaving yourself at least a 6” tail.
    2. Pick up the 1st bar on the other piece.
    3. Insert your needle where the yarn is coming out of the first piece, and pick up the next bar.
    4. Insert your needle where the yarn is coming out of the other piece, and pick up the next bar.
    5. Repeat steps 3 & 4 to complete the seam, pulling it tight every inch or two.

On some pieces, you can pick up 2 bars at a time. This makes the seaming go faster. If you are in doubt, pick up one bar at a time.

You will usually use the same yarn for your seam as you knit with. However, if you are using a weak yarn, like a single ply, you may want to use a stronger yarn for your seam. If you are using a bulky yarn, you may want to use a thinner yarn for your seam to keep it from being too bulky.

Troubleshooting Mattress Stitch

Uneven Pieces

If your pieces are the same length and you seam them perfectly, then you can skip this section. However, if one piece is longer than the other or you inadvertently miss or double up on some stitches while seaming, you may need to make some adjustments. 

Use this technique when one piece is longer than the other or when you are nearing the end of the seam and realize you have more stitches left on one piece than the other. Pick up 2 bars on the longer piece and one bar on the shorter piece. 

Estimate how often to do this. If it’s a small difference to make up, just pick up 2 bars occasionally. If it’s a longer distance, pick up 2 bars more often.

Running Out of Yarn

Don’t worry if you run out of yarn before finishing the seam. Just leave enough tail to sew it in when you are done seaming and start using a new yarn. Leave a tail on the new yarn to sew in later, then overlap the last couple stitches of the old yarn with the first couple stitches of the new yarn (just start the new yarn a stitch or 2 below your last stitch). 

A Project for Practicing Mattress Stitch

Flow is a fantastic project for learning and practicing the mattress stitch. It’s a quick-knit top that is perfect for beginner sweater knitters or those who want to improve their sweater knitting skills. Learn more about our Flow Knit Along, where we guide you step-by-step through the pattern with detailed lessons, at

Flow KAL

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