Ah sewing machine tension. It’s one of those ultra frustrating subjects. If I had a dollar for every time I heard someone say, “I don’t sew much because my machine’s tension was just off”, I’d have a lot of dollars.
Shoot, I gave up sewing for YEARS because I never quite figured out the tension on it. I’m writing this because I don’t want you to be like me.
Go into your closet, pick up a garment you didn’t sew. Look at the front and the back side of the stitch. You’ll notice that the stitch looks pretty much the same on both sides. There’s no weird loops on either side and definitely no nesting thread mess.
If your sewing machine is making loops or loose threads on one side as you stitch, it’s likely that your thread tension is off.
In this lesson, I’ll show you what good sewing machine tension looks like. After that we’ll troubleshoot what could be causing your tension problems, then we’ll get to fix it. I’ll end with telling you when it’s time to run up the white flag.
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What does good sewing machine thread tension look like?
Good tension is balanced tension. When your needle goes down into the fabric, it brings the top thread and bobbin thread together to form a stitch.
When your tension is balanced properly, the stitch should look identical on both sides.
Having balanced tension is important for creating seams that are strong and having stitches that just plain look nice.
What are the right numbers for good thread tension?
Honestly, it kind of depends on your machine and what you’re sewing. The ideal tension setting on your vintage Singer might not be what it is for a newer Janome.
Thicker heavier fabrics will need higher thread tension than lighter weight fabrics. The denim below starts looking good with a top tension of 6 on my machine where the embroidered voile looks best between 4 and 5.
Your own machine probably has a sweet spot where you’ll get good results on most fabrics.
Whenever you get your machine serviced, your repair person will get everything running right for you so that you have a good default tension.
To be true, if you’re constantly adjusting tension numbers, there’s likely something else going on with your machine.
Do this first to check your thread tension
Before we get started, be sure to wind a bobbin with a different color than your top thread.
With contrast thread in the bobbin and the top thread, it’s easy to see where the problem is.
You’re going to be making simple test swatches with a plain cotton. Muslin is great here.
Problems with your sewing machine that get blamed on bad sewing machine tension
Here we’re tackling some problems that end up making your stitches look like the tension is off, but often it’s not.
The reason why we’re starting here and not by having you adjust all your numbers and start pulling out screwdrivers is because it’s often better to rule out these problems first.
You need to clean your machine
Excess lint can really gum up the insides of your machine. And yes, it can make the stitches look like the tension is off.
This problem is easy to fix. Take a small brush and brush out your tension disks. After that, clean out your bobbin case and under the case. Oil things if your machine requires it. For a deeper clean, check out how to clean a sewing machine.
Thread up your machine and make a row of stitches on your test fabric.
Look at both sides of your stitches. Do they look balanced now?
Rethread your machine
Sometimes tension problems are just a matter of rethreading your machine. This is almost always the case if you’ve been stitching without problem and all of a sudden your stitches start looking loopy.
First unthread your machine and thread it up again, paying attention to get the thread into the tension disks. Hold it firmly and be sure you here it click into place.
If you get a big ugly bird’s nest worth of thread on the wrong side of your stitching, first try rethreading your bobbin. It’s easy to get into panic mode when you see something like that, but rethreading almost always helps.
Stitch on your sample fabric and see if it’s better.
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Your needle is damaged or not the right size
Damaged needles can make your stitches go weird on you. If you’ve been sewing and hit something solid like a zipper end, go ahead and change your needle.
You might also be sewing with a needle that’s not the best choice for your fabric. How do you know if you’re doing that? A handy reference book like More Fabric Savvy is a good place to start. Sandra Betzina gives recommendations for stitch length and needles for about every fabric under the sun. I write more about that book in Sewing Books for Beginners That Are Actually Helpful.
When you know what needle you need for the fabric that you’re working with, go ahead and change your needle.
Sometimes all you need to make nice looking stitches is a fresh needle.
Again, stitch another row. Did the needle changing help balance your sewing machine tension?
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You’re using cheapo thread
Friends don’t let friends use cheapo thread. Use a good brand like Mettler, Gutermann or Coats and Clark. I know quilters love Aurifil.
Also skip the “vintage” thread you got at a thrift store. Although you can keep that for basting or because the spools look cool. Just don’t use it in your machine.
This vintage thread below: nice to look at, great for basting, but not so great for actual sewing anymore.
How do you know if you have not great thread?
Hold it in your hands like floss. Pull on the ends. If it snaps, don’t bother sewing with it in your machine.
Your thread has a sharp bit of plastic sticking out
You know those old type of thread spools that have the notch in them where you can tuck in the end of your thread?
Good idea, but definitely you can get stitching problems with them. Usually it’ll look like this: you’ll be stitching along and all of a sudden your stitches start looking really tight on top.
It’s not a tension problem. Simply stop stitching. Chances are that your thread got caught on one of those little notches.
If you use those types of thread spools, load them vertically, and monitor your thread as you stitch. Make sure that the thread is not going to catch that groove as it goes around.
Thread problems when you start stitching
Sometimes when you first start stitching, your thread and or fabric can get pulled downwards. This can cause your top thread to get pulled to the back in a twisty, lumpy ugly looking start. You’ll notice after you get stitching though, your stitches look totally fine. So this in fact, isn’t a problem with tension.
There’s two ways to fix this.
- Use a stitch starter: Start sewing on a folded small piece of fabric in the middle of it. How big? It doesn’t matter. A scrap will do. Just fold it until it’s as thick as the layers of fabric in your seam. You’ll get perfect stitches every time.
- Needle down, not presser foot: The other way to fix this problem is to put your needle down in the fabric with the presser foot up. This is a great fix for delicate, lightweight fabrics that can get sucked down and even stuck in your machine. Use your fly wheel to bring the needle down until it’s just pierced through the fabric. After that, lower your presser foot and keep sewing.
How to fix your sewing machine tension
Now that we’ve ruled out other things that might be making your stitches look less than lovely, let’s get into how to fix your sewing machine tension.
First, stitch on your fabric, making sure again that you have contrasting colors in the upper thread and the bobbin.
Adjusting your upper thread tension
If you see loops on the right side of the fabric, your upper tension is too tight.
If you see loops on the wrong side, the upper tension is either too loose or your bobbin is too tight (read on for how to adjust the bobbin tension).
Lower or raise the number on your upper thread tension dial and try again.
It may be worth stitching a sample at every number just to see when things start getting better or worse. Use a marker and write on your fabric what setting you’ve stitched at.
You can see on my sample here that the top thread peeks through on the lower tensions, starts to disappear around the middle. Then, the bobbin thread starts looping up on top on the tighter settings.
This little sample can be a great reference tool for you, so put it somewhere near your machine for your future self. Make a sample for lightweight fabrics, medium and heavyweight fabrics to give you a good starting point.
Adjusting your bobbin tension
If you have a drop in bobbin like me, you likely can’t adjust your bobbin tension at all.
On the other hand, if you have an older machine with a bobbin case that sits in vertically, here’s how to adjust it.
Pull out your bobbin case, and turn the screw with a small screwdriver. The adjustments to make here are tiny. Don’t turn anything more than ¼ turn either right to tighten or left to loosen. It’s like I tell my violin students: turn it a hair this way or that.
Test your stitches again. Don’t get off in the weeds with adjusting your bobbin. It’s much easier to adjust your top thread than to get obsessed with getting your bobbin 100%.
When you need help fixing your thread tension
If you’ve tried everything and your stitches are still just not right, your machine probably needs a service.
My repair guy always done an excellent job getting my machine in top condition. Know that there is no shame in having to take your machine into the shop. I think a lot of times we sewists have a DIY or die mentality and we see something we can’t fix and it feels like a moral failing. It’s not. Sewing machines are complicated, carefully calibrated things. Unless you repair them yourself, you’re better off letting a professional fix it than spinning your wheels trying to force things into working.
Elizabeth Farr is the writer behind the Elizabeth Made This blog where she shares helpful sewing tips, step by step sewing tutorials and videos to help you explore your creativity through sewing. She has written sewing Eguides and patterns, been a featured teacher at Rebecca Page’s Sewing Summit and Jennifer Maker’s Holiday Maker Fest and her work has appeared in Seamwork and Altered Couture magazines. She also created a line of refashioned garments for SEWN Denver. When her sewing machine isn’t humming, she’s playing and teaching violin, and hanging around a good strategic board game with her husband and 4 kids.