How to Work Mattress Stitch Seams Three Ways
Mattress stitch is a knitting magic trick. It lets you join two pieces of knitting almost invisibly. This technique is worth mastering for a professional finish on all your handknits.
There are three variations of mattress stitch. The one you’ll use depends on which edges you are joining. Vertical mattress stitch is used to join rows to rows, such as for a side seam or a sleeve seam. Horizontal mattress stitch joins cast-on or bound-off stitches, such as for a shoulder seam. And perpendicular mattress stitch joins stitches to rows, such as for sewing a sleeve to an armhole edge. Let’s take a close look at all three.
Related: Better Sweaters: Adding Structure with Seaming
Mattress Stitch Three Ways: Watch Now
For more detail on each method, we have step-by-step tutorials below for vertical, horizontal, and perpendicular mattress stitch.
Related: How to Seam Garter Stitch with Mattress Stitch
Vertical Mattress Stitch
Vertical mattress stitch is usually worked in the space between the first two stitches. The edge stitch becomes your seam allowance and disappears into the seam. For these photos, I’m using a contrasting-colored yarn for seaming, but you’ll use the same yarn as you used to knit your pieces, or a thinner yarn in a matching color.
1
Thread your tapestry needle with your seaming yarn. Bring the needle up from the wrong side to the right side between the first and second stitch of the first row, just above the cast-on edge.
2
On the other side, take the needle down to the wrong side between the first and second stitch of the first row, just above the cast-on edge. Bring it to the right side in the very next row. You’ll see that you’ve caught one “bar” with your needle. This bar is the strand of yarn that runs between the two stitches. Keep your stitches loose while you’re working.
3
Move back to the first side and insert the needle from right side to wrong side in the very same space where the yarn is coming up, then bring it to the right side two rows above this point. You’ll see that you’ve caught two “bars” with your needle.
4
On the other side, insert the needle from right side to wrong side in the very same space where the yarn is coming up, then bring it back to the right side two rows above this point. You’ve caught two bars.
Pulling Tight
5
Repeat Steps 3 and 4 until you have a couple of inches worth of rows loosely sewn together.
6
Here is the magic part: pull firmly on the sewing thread to draw the two sides together. Your seam almost disappears.
After pulling the seam closed, grasp each end of the seam and pull to stretch it a bit. This settles the stitches and eases the sewing yarn so it’s not too tight.
Keep going, moving from one side to the other and catching two bars with each stitch. Stop every couple of inches and pull the seam closed, then stretch the seam.
Horizontal Mattress Stitch
With horizontal mattress stitch, instead of joining two rows (two bars) to two rows, you’ll join one stitch to one stitch.
Find a full photo tutorial for horizontal mattress stitch here.
Perpendicular Mattress Stitch
Perpendicular mattress stitch joins stitches along a cast-on or bound-off edge to rows along a side edge. This is most commonly used to sew a sleeve into an armhole.
The challenge with sewing rows to stitches is that they are usually not the same size. And the ratio between stitch width and row height will change depending on your stitch pattern. To create a smooth seam, we need to consider gauge. Most of the time, you’ll be joining 2 stitches to every 3 rows, 3 stitches to every 4 rows, or 4 stitches to every 5 rows.
Determining Your Seam Ratio
In my stockinette stitch swatches, my gauge is 19 stitches and 26 rows = 4″. Here is how we determine the ratio for our seam:
Stitch gauge divided by row gauge equals ratio.
For my swatches: 19 / 26 = .73
That .73 ratio is very close to 3/4, so we’re going to join three stitches to every four rows. This means we’ll join one “bar” to one stitch, the next bar to the next stitch, then the next two bars to the third stitch. Remember, each “bar” on the vertical side of your seam represents one row of knitting. For each stitch on the horizontal side of your seam you’ll need to catch both legs of the stitch.
This little bit of math is all you need to produce a perfectly smooth seam.
Beautiful Seams Make Beautiful Projects
Don’t limit your knitting options by avoiding seams! With just a little bit of practice, you too can become a Master of Mattress Stitch (I think we need a badge).
Sandi Rosner is the technical content editor for all things yarn at Interweave. When she isn’t knitting, she usually has her nose in a book. You’ll find new technical content from Sandi nearly every week at www.interweave.com.
Seam It With Mattress Stitch
Very good, clear tutorial. However — I use crochet cotton, usually #10, to sew knitted garments together. I think it is more suitable — sturdier and less stretchy than knitting yarn.
If you examine ready-made sweaters, you will not find them stitched with knitting yarn. Try crochet cotton. Your seams will be much more durable.
Excellent tutorial! Would be interested to see this technique used on garter stitch. Not sure if seaming garter edges would play as nicely as stockinette does in all directions (vertical, horizontal or perpendicular).
Thanks! I’ve added mattress stitch on garter stitch to my list of posts to-be-written.