How to adjust the thread tightness on a sewing machine?

Adjusting the thread tension is an essential step to achieve neat and balanced stitches. Poorly adjusted tension can cause irregular stitches, puckered fabric, or thread that breaks easily.

In this article, discover how to adjust the thread tension on a sewing machine and how to identify common problems for flawless finishes .

Why is adjusting the thread tension so important?

Thread tension determines the way the upper and lower threads interlock to form a stitch. A good adjustment allows you to achieve:

• A neat and regular straight stitch without borders or loops.
• A balanced zigzag stitch , ideal for stretch fabrics.
• A strong seam, without the risk of the thread coming undone.

Poorly adjusted tension can cause visible irregularities on the right or wrong side of the fabric, which affects the quality of the work.

How to know if the thread tension is properly adjusted?

A stitch is properly adjusted when:

• The threads are balanced on both sides of the fabric .
• The fabric is flat and shows no puckering or distortion.
• The upper thread and bobbin thread interlock in the middle of the fabric, without being visible on either the front or the back.

How to adjust the upper thread tension?

The upper thread tension is adjusted using of a graduated dial on the machine.

• Increase the tension (higher number) if the upper thread is too loose and visible on the back of the fabric.
• Decrease the tension (lower number) if the upper thread is too tight and puckers the fabric.

What to do if the thread tension is too loose?

See tension image numbers 1, 2, 3, 5, 6, 7.

If the upper thread is too loose (visible on the back of the fabric) :

• The thread is not tight enough and forms loops on the back of the fabric .
• Solution: gradually increase the upper thread tension until the stitches are well balanced.

If the lower thread is too loose (visible on the right side of the fabric) :

• The bobbin thread is too loose and shows on the right side.
• Solution: slightly decrease the upper thread tension or adjust the bobbin tension if necessary.

Testing on a similar piece of fabric before starting a project helps avoid these problems from the start.

How to avoid too tight tension?

See tension image number 4.

Too much tension causes uneven stitches and puckering fabric.

• If the fabric puckers and the upper thread is visible on the right side, slightly decrease the upper thread tension.
• If the stitches seem stiff and hard to sew, check that the bobbin thread is not too tight.

How to adjust tension for different types of fabrics?

For thin and lightweight fabrics

(Corresponding image: sewing on light fabric with good tension adjustment)

• Slightly decrease the upper thread tension to avoid pulling on the fabric.
• Use a standard polyester thread and a suitable needle for smooth sewing.

For thick and stiff fabrics

• Slightly increase the upper thread tension to allow good thread penetration.
• Check that the machine is feeding the fabric properly without forcing it.

For stretch fabrics

• Choose a zigzag stitch or a stretch stitch to prevent the seam from breaking.
• Adjust the thread tension to allow good elasticity without puckering the fabric.

How to check the tension setting before sewing?

Before starting a project, it is recommended to:

• Test the sewing on a sample of the same fabric.
• Check the stitch balance and adjust the tension if necessary.
• Regularly check the thread tension if you change the type or thickness of fabric.

Conclusion  

Correctly setting the thread tension is essential for achieving a regular and durable stitch.

• A balanced stitch shows no loops or visible threads on the front or back.
• Gradually adjust the upper thread tension based on the results observed.
• Check the tension before starting a project to avoid sewing defects.
• Adjust the tension according to the type of fabric, whether it is thin, thick, or stretchy.

By applying these tips, your seams will be precise, strong, and perfectly suited to each fabric .