How you seam can make or break your knitting project. Learn how to make almost invisible seams with mattress stitch in this step by step tutorial.
I’ll show you how to seam a knit hat using my free beginner beanie hat pattern but you can use the same mattress stitch technique to neatly seam any knitting project.
Note: I’ve a separate mattress stitch for ribbing guide here.
Table of Contents
Mattress Stitch Video Tutorial
There’s also step by step written instructions below if you prefer:
How to Seam Stockinette Knitting with Mattress Stitch
Most Important: Where to Put your Needle
The tricky bit about mattress stitch is knowing exactly where to put your needle.
The golden rule with mattress stitch is you work 1 stitch in from each side.
That sounds simple enough, but stockinette edge stitches always look a bit messy and where exactly do you put your needle to get this magic invisible seam?
Well, if you look at the better behaved stitches in the middle of your knitting, you see that stockinette is made up of columns of v shape stitches.
And if you stretch your knitting apart, you see little horizontal bars everywhere that look like rungs of a ladder.
There’s a ladder going down the middle of each v shaped stitch column and also a ladder between each stitch column.
To do mattress stitch, you work in the ladder between the first 2 stitch columns on each side, putting your needle through the bars.
Find the 1st and 2nd Stitches
Look at your stockinette edges and identify the 1st and 2nd stitches.
If you start a few stitches in, it’s easy enough to see the v stitch columns. So count out from here towards the edge you’ll see a last fairly clear v stitch column and then a messier version curling around the back.
So you’re going to work in between these 2 columns, with a fairly orderly looking v stitch column on 1 side of your needle, and the messy edge stitch on the other.
The idea is that the column of V stitches from both sides end up lying right beside each other looking like the middle of your knitting so the seam disappears.
What if you’re Seaming Upside Down?
If you’re seaming a hat or sleeve from the top down, your knitting is upside down as you seam.
So your stitch columns are made up of upside down v shapes instead.
Or, you’re looking for columns of arrows or chevrons that point upwards now instead of down.
They actually look like little pairs of trousers to me. Whatever works!
So you still work under the ladder bars, but you want arrows pointing up (or trouser legs) on one side of your needle instead.
Prepare for Seaming
While you learn, it helps to pin the sides together before you start so your seam stays even and lines up at the bottom, but it’s not vital.
Leave the first 5 inches open approx so you have space to work.
Thread a tapestry needle with your long yarn tail if available or else a new length of the same yarn you knit with.
Note: I’m using a contrasting colour in the pictures and video in this guide to make the demo clearer and to show you how invisible a mattress stitch seam is.
Step 1: Go Under 2 Bars on 1 Side
You always work mattress stitch 1 stitch in from each side.
So starting on the opposite side to where your yarn tail is coming from, look for the 1st column of v shapes if you’re working from the bottom up.
Or if you’re seaming upside down as in this hat demo, look for the 1st column of upward pointing arrows, or little trousers as I like to call them. Technically this is the 2nd stitch with the messy edge stitch beside it.
If you pull apart gently, you see the horizontal ladder bars between the 1st and 2nd stitch. You’re always going to put your needle in this channel, under a couple of bars at a time.
So put your needle under the 1st 2 bars you can see and pull it through most of the way. Leave the yarn a bit loose at the opening.
Step 2: Go Under 2 Bars on the Other Side
Now repeat step 1 on the other side. Look carefully for the first column of v shapes (or upward pointing arrows if seaming a hat or sleeve from the top down).
Pull apart and you will see the little horizontal bars between the 1st and 2nd stitches.
Put your needle through under the first 2 bars. Pull the yarn through loosely again.
So now we have started the seam on both sides. That’s actually the hard part over with!
Once you start the seam in the right place, it’s easy to see where to seam the rest.
Step 3: Repeat Steps 1 & 2 Several Times
Go back to your 1st side, and put your needle in to exact same spot you came up through, right where you see the loose yarn seam.
Put it through under the next 2 bars you see in front of the needle and pull through loosely.
Now do the same on the other side. Put your needle back down into the same place as before, bring it under the next 2 little bars you see across, and pull it through gently.
You will start to see this nice loose zig zag pattern between the 2 sides.
Repeat this several times. It’s always the same step on each side: put your needle into the exact same spot as before, go under the next 2 bars and pull through loosely.
Step 4: Pull to Make your Seam Disappear
Finally it’s time for the magic! All you do is hold both sides together and give your yarn a good long pull to close the seam.
Hey presto! You have an invisible seam. OK it’s not quite invisible, but the seam blends in very well.
If you really pull the seam apart you can see little flecks of the contrast colour yarn I’m seaming with. But because you will be using the same yarn you knit with, your seam will look seamless. That’s the magic of of mattress stitch.
Step 5: Repeat Steps 1-4 until the End
Now just repeat these steps until the end of the stockinette, seaming a chunk at a time and then pulling to make the seam disappear.
How Stockinette Mattress Stitch Looks on the Inside
The magic of mattress stitch is it’s nearly invisible on the outside. But here’s how it looks on the inside.
Because you work mattress stitch 1 stitch in from both sides, the 2 edge stitches make a raised ridge on the inside.
And because I’ve used a contrast seam colour, you can see a line of straight stitches running down both sides of the ridge.
While mattress stitch looks great and makes a secure seam, there’s substantial seam bulk on the inside.
Tip: if you’re making hats for sensitive heads, especially chemo caps, I recommend knitting them in the round instead so they’re seam free.
See how to get started knitting hats in the round in my video tutorial and I’ve a free knit in the round beginner hat pattern too.
Mattress Stitch Seaming Tips & Common Problems
Tip 1: Keep the End of the Seam Loose
It can a bit tricky to start seaming again after you’ve pulled your seam because everything has tightened up.
So tip 1 is to loosen the end of the seam, so it’s easy to see exactly where to put your needle again.
Note: Gaps Between Bars Vary
Sometimes the next 2 bars will be really close together and other times there’ll be a larger gap between them.
It’s natural for hand knitting to vary like this, but once you always go under 2 bars at a time, your seam will line up just fine.
Tip 2: You May Need to Pull Twice
After you have seamed a chunk of stitches, you may need to pull a couple of times to close all the seam, especially if you seam longer sections at a time.
Tip 3: Check for a Smooth Seam
Check the tension along your seam after each section. Feel along and around it. You want a nice, smooth even seam.
So if bits feel too tight or loose, gently pull at both sides and along the seam to adjust and even it out before you move on.
Tip 4: How to Fix Uneven Lengths
While your seam should automatically line up on both sides, it’s worth a quick check now and then if you didn’t pin the sides together.
The good news you can fix uneven lengths by going under just 1 bar on the shorter side every 2nd time until the lengths match.
By still always going under 2 bars on the longer side, you seam a bit more fabric which evens things out.
Tip 5: Pin the Sides at the Start
The fix in tip 4 is really more of a hack, and your mattress stitch won’t look quite as good.
So Tip 5 is to pin the sides together at the start until you’re confident mattress stitching. This extra measure helps your hat edges line up perfectly.
How to Seam Ribbing with Mattress Stitch
You can also use mattress stitch to seam rib stitch which really does look invisible.
You use the same loose side to side technique and pull at the end. But where you put your needle is quite different.
Watch the video above from the 10 minute marker or see my separate mattress stitch for rib guide for step by step instructions.
I hope this guide helps you master mattress stitch. It really helps give your knitting projects a neat finish you can be proud of. Got any questions? Just comment below and I’ll try to help.