Thread Tension Explained (Without the Boring Math)

Let’s be real: thread tension is one of those things everyone pretends to understand, but most of us are just fiddling with dials and hoping for the best. The good news? You don’t need a physics degree or a ten-page manual to get it right.

Here’s a quick guide to thread tension: what it is, why it matters, and how to fix it when it’s being a bitch.

What Even Is Thread Tension?

Thread tension is basically how tightly your sewing machine is pulling on the thread—top thread, bottom thread, or both. If the tension is off, your stitches might look weird, loose, loopy, tight, or just plain wrong. If it’s balanced, your stitches are smooth and even, and your fabric isn’t puckering or gathering.

In simple terms:

• Too tight = your thread is being pulled too hard → fabric might pucker, thread might break.

• Too loose = your stitches look loopy or messy → you might see weird thread nests or skipped stitches.

The Two Culprits: Top & Bobbin Tension

Most of the time, you’ll be adjusting the top thread tension, which is controlled by that little numbered dial on your machine. The bobbin tension is more hidden and rarely needs adjusting—unless things are seriously out of whack.

Pro tip: If you’re new to adjusting tension, start with the top thread first. The bobbin side is more sensitive and usually set by your machine manufacturer.

What Should Good Tension Look Like?

• The top and bobbin threads should meet in the middle of your fabric.

• You shouldn’t see the top thread pulling to the back, or the bobbin thread showing on the top.

• The stitch should look smooth and even on both sides. No loops, no pulling, no drama.

  
  

If your stitches look suspicious, don’t panic. It’s probably just tension (and yes, that includes your tension too—we get it).

How to Fix Tension Without Screaming Into the Void

1. Test on a scrap of the same fabric you’re working with (and use the same batting/thread combo too).

2. Start by adjusting your top thread dial.

   • If your bobbin thread is showing on top, lower the top tension.

   • If your top thread is getting pulled to the back, raise the top tension.

3. Go slow and adjust by half a number at a time.

4. Stitch a few inches, then check both sides.

5. Repeat until your stitch is just right.

Helpful tip: make a note of what your original tension was set at before you change it — that way, if it gets worse, you can always go back!

A Few Common Thread Tension Freakouts (And What They Mean)

• Bird’s nest on the back?

  • Your top thread probably isn't threaded correctly. Rethread it completely with the presser foot up. Yes, up.

• Loops on top?

  • Bobbin tension might be too loose—or your top tension is too high.

• Fabric puckering?

  
  
  
  

  • Top tension might be too tight or you’re using the wrong needle/thread combo.

• Skipped stitches?

  • Could be tension, but also check your needle—it might be dull or bent.

The Verdict

Thread tension might seem intimidating, but it’s really just trial, error, and a little patience (sometimes maybe a lot). Once you learn what "right" looks like, your machine will start to feel way more predictable—and less like it's actively trying to sabotage you.

Time to make some cool shit! ✂️💗

-Manon