My Thread Tension Looks Wrong - What Should I Adjust?

If your stitching looks less than perfect, you're seeing the wrong thread on the wrong side of your fabric, or you're getting loops underneath your work, the top thread tension is often the first thing to check.

With correct tension, the top and bobbin threads meet inside the fabric layers rather than being pulled visibly to either surface:

If you can see the top thread on the underside of the fabric

Your top thread tension is too low - as the top thread hasn't got enough tension to pull the bobbin thread up high enough. 

Increase the top thread tension by turning the tension setting to a higher number.

This is the one I see people often have issues with when sewing bags.

If you can see the bobbin thread on the top of the fabric

Your top thread tension is too high - as the high tension is pulling your bobbin thread up and making it visible on the top of your project.

Decrease the top thread tension by turning the tension setting to a lower number.

This is fairly uncommon when sewing thick bag-making layers, assuming the machine is threaded correctly.

What if I'm getting loops underneath?

Loops forming on the bottom of your stitching usually mean the top thread isn't under enough tension - or that it hasn't entered the tension discs properly at all.

Before changing the dial dramatically, I would first:

• Raise the presser foot
• Completely rethread the top thread
• Make sure the thread is seated properly in the tension discs
  
• Blow hard in-between the tension discs to dislodge any dust or thread scraps that might be interfering with the tension
• Check that the machine is threaded correctly from beginning to end 

Then test again on a scrap made from the same materials as your project.

If the loops remain, gradually increase the top thread tension and test after each small adjustment. 

On the Husqvarna Opal 690q and many similarly constructed domestic machines, the tension discs are "hidden" in the first (to the right) vertical opening the thread goes through when you thread your machine.  So not the left opening with the little "lever" that goes up and down as you sew. 

A good basic rule to remember is:

Problems showing on the top of your project usually point to the bobbin thread.

Problems showing on the bottom of your project usually point to the top thread.

Before you start changing tension settings

If your tension suddenly looks wrong when the machine was sewing perfectly a moment ago, I wouldn't immediately assume the tension dial has somehow changed.

Rethread both the top thread and bobbin first.

When rethreading the top thread, keep the presser foot raised so the tension discs are open and the thread can sit correctly between them.

If necessary, you can also clean between the upper tension discs to remove any dust or thread residue.

Make small adjustments

Don't jump from one extreme to the other.

Change the tension a little at a time and sew a short test line after each adjustment. Use the same thread, needle, fabric and stabiliser combination as the area that's giving you trouble.

You're looking for the point where the top and bobbin threads meet neatly inside the layers, rather than being pulled visibly to either surface.

What about the bobbin tension?

I generally recommend leaving the bobbin tension alone unless you've already ruled out everything else.

Bobbin tension adjustments vary quite a bit between machines, and on many domestic machines they're rarely necessary to touch for normal bag sewing.

If you've rethreaded, cleaned the machine and tried the full useful range of your upper tension setting without getting a balanced stitch, check your sewing machine manual before adjusting the bobbin tension.

Are you actually getting skipped stitches?

If the machine is leaving complete gaps where stitches should be, that's a different problem.

Changing the thread tension usually won't fix skipped stitches.

→ My Sewing Machine Is Skipping Stitches 

Still not sure which way to adjust?

A simple rule to remember:

Bobbin thread showing on top = decrease top tension.
Top thread showing underneath = increase top tension.