What Is Auto Tension On A Sewing Machine

Machine tension is an important aspect of ensuring that your sewing is perfect. With the proper tension, your sewing projects are perfect. Your threads are properly sewn on the fabric. There are no loose ends. The top thread and the lower thread on your sewing machine must correspond and align when your sewing machine is working at the right tension.

What Is Auto Tension On A Sewing Machine?

Auto tension or automatic tension on your sewing machine is the ability of your sewing machine to assess your fabric’s thickness and set the tension required by the sewing thread automatically.

How Does Auto Tension In Your Sewing Machine Work?

Computerized sewing machines are the ultimate auto tension sewing machines. This is because they contain electronic sensors that can easily assess the thickness of a fabric and adjust the tension of the sewing thread.
Auto tension in a sewing machine means that your sewing machine has a thread tension controller that holds the upper thread at an already provided tension so as to control the force and amount of top thread that goes into a stitch.

Sewing Machine Auto Tension By Stitch Type

This is a type of sewing machine auto tension that doesn’t focus on the fabric. Rather, its main focus is the thread and stitches made.
This tension is then set by dial or via sewing machine screen depending on the type of your sewing machine. As opposed to automatically set tension, this type of tension setting is more manual than it is automatic.

Auto Tension In Mechanical Sewing Machines

Mechanical sewing machines do not have auto tension. Normally, they come with a preset sewing machine tension for the top thread. It is set between 4 and 5 which is known as the universal tension.
Tension on a mechanical sewing machine can be set manually depending on the type of thread, needle and fabric being used to sew.

How To Test Your Sewing Machine Tension?

On a 5-inch piece of fabric, stitch on a straight line from one end to the other. Hold the ends of the stitched line and pull until the threads break. If the stitches on the opposite ends break at similar positions, you have perfect tension and you can start sewing.

Benefits Of Automatic Tension

The biggest benefit of automatic tension, you can expect to experience the best stitch quality for every type of fabric that you use to sew. This is because thread tension is controlled automatically by the sewing machine.

Factors To Consider When Dealing With Sewing Machine Tension


Sewing machine tension is usually tested at the thread. Without proper tension, the thread at the top and the bottom do not coordinate their work effectively. As a result, your bobbin thread and your needle thread are each seen on the opposite sides of the fabric which should not be the case.
With poor tension, the threads are loose and the sewing machine moves awkward or doesn’t move at all. It is important to thread your sewing machine properly and to use high-quality threads for proper tension.
Also, make sure that as much as you can, the bottom and top threads are of the same quality and strength.


Without needles, there would be no sewing. Sometimes, using the wrong needles or using blunt needles may affect the tension of a sewing machine. Change your needles regularly as advised by your sewing machine manufacturer or when it’s blunt and battered.


Fabrics and threads break down into the sewing machine. They can accumulate in the sewing machine and mix with the lubricant oils to become dirt. Accumulated dirt in the sewing machine will often affect tension. Clean your machine regularly to avoid this.

Sewing Machine Settings

When the tension in your sewing machine is loose, it is important to check whether the tension dials have been touched. If they have, restore them to their original settings to get back to the correct tension level.

Bobbin Thread

The bobbin case and thread that it holds are significant aspects of the normal tension of a sewing machine.
The bobbin holds the lower threads. Make sure that the bobbin case and threads are in place normally to ensure sewing machine auto tension. Also, confirm that the bobbin winding is not too tight or too loose. This may also cause tension problems with your sewing machine.


Depending on the fabric you are working on, you may need to adjust the tension of your sewing machine from the auto to another lever that comfortably handles the fabric. Some heavy fabrics will also require different kinds of threads and needles.
If you have a problem with your sewing machine tension, consider checking on all these factors first before adjusting the tension. When the problem persists, you can now consider adjusting the auto tension of your sewing machine.
Here are the steps to follow to get the best sewing machine tension for your project.

How To Adjust Tension In Your Sewing Machine?

  1. Test what part of the sewing process has a tension problem. It could be the top or bottom threads. Sew through a piece of the fabric that you will be using.
  2. Inspect the threads. If your bottom and top threads are aligned properly, you don’t have a tension problem. When they are not, then, you need to adjust your tension. If either the bobbin thread or top thread is seen on their opposite sides as not straight, you need to adjust your sewing machine tension.
  3. Start by making sure that your sewing machine is in the proper condition. Confirm that there is no dirt blocking the movement of needle and thread while sewing and that it is properly threaded. Also, use new needles for every new project.
  4. Move your tension dials slowly to adjust the tension on the top thread. Increase the tension range if the top is loose and lower the tension range if it is too tight. The top thread is loose if it shows on the bottom of the fabric while the bobbin thread is straight. In this case, increase the tension on the dials. If it is too tight, reduce the tension on the dials.
  5. Adjust the tension on the bobbin thread. Pull the threads that are visible before you start sewing. If your bottom thread pulls easily or can be seen to be loose, you need to adjust its tension. A screwdriver is all you need in this case. Using the screwdriver, turn the screw located near your bobbin case right to increase tension and left to reduce the tension.
  6. Sew your test fabric to confirm that you now have the right tension. If not, follow the above steps until you have perfect tension.
  7. Normally, the bobbin tension is not adjusted. You adjust the bobbin tension only when you are working with tough fabrics such as canvas. Adjust your top thread tension until you get it right. Normally, preset auto-tension for many sewing machines is between 4 and 5 on the tension dials.
  8. When you are sure that you have your tension right, you are now ready to embark on your project. Remember to keep your sewing machine clean and to change your needles often after a long period of use.

Many sewing machine users are afraid of adjusting their sewing machine tension. These few steps eliminate the fear and make the process easy to follow and complete perfectly.

If you have tried these steps on your own and your threads are still loose and puckering, you will need to consult a professional. It is best if you contacted your sewing machine supplier who will send in technicians to help you. You could also call the manufacturer’s customer support center. You will be guided on the phone on how to solve the issues and get back to sewing.


Sewing machine auto tension is set by the manufacturers. Sewing machine users advise that if you are facing any tension problems, don’t rush to adjust the dials. First, consider all the other factors that could cause problems such as threading, quality of needles, and dirty sewing machines. If the problem persists, you can use the steps above to adjust the tension on your sewing machine.



I'm Jessica Flores, a professional fashion designer and an expert seamstress. Crafting has always been a deep-seated passion of mine, one that has flourished and evolved over the years. I've dedicated considerable time to both studying and practicing in the realm of fashion and sewing, amassing a wealth of experience and skills. It brings me great joy to share these insights and experiences with you all, hoping to inspire and foster a similar passion for the art of sewing.

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