Troubleshooting How To Adjust Tension On Sewing Machine

Do your sewing stitches look messy? Are threads looping on your fabric? This often means your sewing machine tension is off. Learning how to adjust tension on your sewing machine fixes many common sewing machine tension problems. It is a key skill for making strong, nice-looking seams. This guide will show you how to fix sewing machine tension problems step by step, covering upper thread tension and bobbin case tension. We will help you get correct thread tension for your projects.

How To Adjust Tension On Sewing Machine
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Learning About Thread Tension

What is thread tension on a sewing machine? Think of it like a small tug-of-war between the top thread and the bottom thread. Your machine pulls both threads. They meet inside the fabric layers. They link together to form a stitch.

For a stitch to be strong and look good, the pull on both threads must be just right. They must pull with equal strength. When the pull is not equal, you get sewing machine tension problems. The stitch will look wrong.

Upper Thread: Comes from the spool on top of your machine. It goes through guides and tension discs.
Bobbin Thread: Comes from the bobbin below your needle plate. It sits in a bobbin case tension system.

The tension system puts a little drag or pull on the threads. This makes them link tightly in the middle of the fabric sandwich.

Seeing Trouble: Sewing Machine Tension Problems

How do you know if your tension is bad? Your stitches will tell you. Here are the most common signs of sewing machine tension problems:

Loose Stitches Sewing Machine

This is the most common issue. It means one thread is not being pulled tightly enough. The other thread pulls it into loops.

Loops on the Bottom of the Fabric: If you see loops of thread on the bottom side of your fabric, the top thread tension is too loose. The bottom thread is pulling the loose top thread downwards. This is a classic sign of needing to adjust upper thread tension. You will see thread loops on fabric.
Loops on the Top of the Fabric: If you see loops of thread on the top side of your fabric, the bottom thread tension is too loose. The top thread is pulling the loose bottom thread upwards. This means you might need to adjust bobbin tension.

Tight Stitches Sewing Machine

This happens when one or both threads are being pulled too tightly.

Pulled or Puckered Fabric: If your fabric looks wavy or gathered along the seam, the tension is too tight. The threads are pulling the fabric in. This can happen with either or both threads being too tight.
Thread Breaking: If your thread keeps snapping, it might be too tight. The thread cannot handle the stress of being pulled through the fabric.
Stiff Seams: Seams that feel hard or stiff can mean the tension is too high.

Unbalanced Tension

This means the top and bottom threads are not meeting neatly in the middle of the fabric.

Good tension: Top thread and bobbin thread meet neatly in the middle of the fabric layers. They look like they are holding hands right inside the fabric.
Bad tension: One thread lies flat on one side of the fabric, and the other thread wraps around it on the other side.

Looking at your stitch on a test piece of fabric is the best way to see if tension is balanced.

Things to Check First: Before Adjusting Tension Dials

Often, bad stitches are not caused by the tension dials being set wrong. Many other things can make your stitches look bad. Always check these things before changing your tension settings. This is key for troubleshooting sewing machine tension.

Your Thread

Is it High Quality? Cheap thread can have thick and thin spots. This makes tension uneven. Use good quality thread from a known brand.
Is it Right for Your Fabric and Needle? Heavy thread needs a bigger needle and maybe different tension than thin thread. Using very different threads in the top and bobbin can cause problems.
Is it Old? Old thread gets weak and breaks easily. It can also lose its smoothness.
Is it on Straight? Make sure the spool or cone is on the pin correctly. It should unwind smoothly.

Your Needle

Is it Right for Your Fabric? Use the right needle type (universal, ballpoint, sharp, etc.) and size for your fabric. A needle too big or too small can affect stitch quality.
Is it Bent or Dull? A slightly bent or dull needle does not make a clean hole in the fabric. This makes the thread struggle. It can cause skipped stitches or poor tension. Change your needle often! Needles are cheap.
Is it Put in Right? Make sure the needle is all the way up in the machine’s needle clamp. Make sure the flat side is facing the right way (usually to the back on most machines). If it’s not in right, it can’t pick up the bobbin thread correctly. This looks like bad tension.

How Your Machine Is Threaded

Is it Threaded Correctly? This is a huge cause of tension problems. Even missing one guide can make the top tension zero. Always thread your machine with the presser foot UP. This opens the tension discs. If the foot is down, the discs are closed, and the thread cannot go in correctly.
Did You Skip a Guide or Hook? Go slowly and follow your machine’s threading path exactly. Check every hook and guide.
Is the Thread Tangled? Check for knots or twists in the thread on the spool or on its way through the machine.

Your Bobbin

Is it Wound Evenly? The thread should be smooth on the bobbin, not lumpy or messy. Bobbins wound too loosely or too tightly cause bobbin case tension issues.
Is it Put in Right? Make sure the bobbin is in its case or holder the correct way. There’s usually a specific direction for the thread to come off (check your manual).
Is the Bobbin Case Clean? Lint and bits of thread can gather in the bobbin case area. This affects the smooth pull of the bobbin thread.

Your Fabric

Is it Clean? Very linty fabrics can clog your machine quickly.
Is it Laying Flat? Pulling or pushing the fabric while sewing messes up stitch length and tension. Guide the fabric gently.

Lint and Dust

Clean Your Machine! Lint under the needle plate, in the bobbin case, and around the tension discs can mess up tension. Clean your machine regularly. Use a small brush. Do not use canned air inside the bobbin area of a front-load machine, it can push lint deeper.

Before you touch any tension dial, always do these checks:
1. Change the needle.
2. Remove all threads (top and bobbin).
3. Clean the bobbin area and under the needle plate.
4. Rethread the top of the machine with the presser foot UP.
5. Put the bobbin back in correctly.
6. Sew a test seam on a scrap of your fabric.
7. Look at the stitches. Is the tension still bad? If yes, then it is time to adjust the dials.

Adjusting the Top Thread Tension

The sewing machine tension dial controls the upper thread tension. This is the dial you will adjust most often.

Finding the Tension Dial

On most machines, the dial is on the front or side of the machine, near where the top thread goes in after leaving the spool.
It usually has numbers. A common range is 0 to 9.

What the Numbers Mean

Higher Numbers: Mean more tension. The machine pulls the top thread tighter.
Lower Numbers: Mean less tension. The machine lets the top thread flow more freely.
Middle Number (often 4 or 5): This is the normal or default setting. Start here for most sewing.

How to Adjust Upper Thread Tension

You will adjust this dial based on what your stitches look like on your test fabric.

Prepare a Test Piece: Get a scrap of the fabric you are sewing. Fold it in half so you are sewing through two layers, just like a real seam.
Set to Normal: Make sure your sewing machine tension dial is set to the middle number (like 4 or 5).
Sew a Test Line: Sew a few inches of a straight stitch on your fabric scrap.
Look at the Stitch:
- Turn the fabric over. Look at the bottom side.
- Are there loops on the bottom? (Looks like little messy nests). This means the top thread is too loose. It is not being pulled down enough. The dial number is too low.
- Turn the dial to a slightly higher number (maybe move from 4 to 5).
- Sew another test line on a fresh spot on your scrap.
- Look at the stitches again. Is it better? Keep going up by small amounts (half a number or one number at a time) and testing until the loops on the bottom go away.
- Does the seam look tight or is the fabric puckering? (Looks pulled or gathered). This means the top thread might be too tight, OR the bobbin thread is too loose.
- Are there loops on the top? This means the bottom thread is too loose, or the top thread is too tight. The dial number might be too high.
- Turn the dial to a slightly lower number (maybe move from 5 to 4).
- Sew another test line.
- Look again. Is it better? Keep going down by small amounts and testing until the top loops or tightness go away.
Aim for Balanced Tension: The goal is for the stitches to look the same on the top and bottom of the fabric. The threads should meet inside the fabric layers. You should not see loops on either side. The seam should lie flat.

Rule for Upper Tension:
* Loops on the bottom -> Top tension too loose -> Increase the number on the dial.
* Loops on the top -> Bottom tension too loose -> (Or Top tension too tight) -> Decrease the number on the dial. (We will talk about adjusting bobbin tension next, but usually you try adjusting the top first).

Always make small changes to the sewing machine tension dial. Sew a test line after every change. This lets you see what each small move does.

Stitch Problem on Fabric	What it Looks Like	Likely Cause(s)	First Thing to Try (After basic checks)
`Loose stitches sewing machine`	`Thread loops on fabric` – on the bottom	Top thread too loose	Increase `upper thread tension` dial #
`Loose stitches sewing machine`	`Thread loops on fabric` – on the top	Bobbin thread too loose OR Top thread too tight	Decrease `upper thread tension` dial # (or adjust bobbin later)
`Tight stitches sewing machine`	Fabric is puckered or pulled	Tension too tight (top or bottom)	Decrease `upper thread tension` dial #
Thread breaking often	Thread snaps during sewing	Tension too tight (top or bottom)	Decrease `upper thread tension` dial #

Adjusting the Bottom Thread Tension (Adjust Bobbin Tension)

Adjusting the bobbin case tension is less common. Most sewing problems can be fixed by adjusting the upper thread tension. Only adjust the bobbin tension if:

You have checked everything else (needle, threading, bobbin winding, cleaning).
Adjusting the top tension dial does not fix the problem, or the problem is very clearly loose stitches only on the top of the fabric (meaning the bobbin thread is too loose).
You are using specialty threads (very thick, very thin) that require it.

Bobbin tension is controlled by a small screw on the bobbin case tension spring.

Types of Bobbin Cases

Front-Load (or Side-Load): The bobbin case is separate. You put the bobbin into the case, then put the case into the machine. These usually have a visible screw on the outside of the case.
Drop-In (or Top-Load): The bobbin drops directly into a holder under the needle plate. The tension is controlled by a spring built into the machine’s bobbin area. Adjusting this type can be harder and sometimes requires a service tech. We will focus on adjusting the front-load type with the visible screw, as it’s the one meant for user adjustment.

Locating the Bobbin Case Tension Screw

If you have a front-load machine, take out the bobbin case.
Look on the side of the case. You will see a small flat metal spring that the bobbin thread passes under.
There is a very small screw holding this spring. This is the bobbin case tension screw. There might be two screws; adjust the one holding the larger, flat tension spring.

Making Small Adjustments to Bobbin Tension

You need a small screwdriver. An eyeglass repair screwdriver works well.
Remember: VERY small turns. Think of the screw like a clock face. Move it just like turning the minute hand from 12 to 1 or 12 to 11.
To Increase Bobbin Tension (make it tighter): Turn the screw slightly clockwise (to the right). This puts more pressure on the thread.
To Decrease Bobbin Tension (make it looser): Turn the screw slightly counter-clockwise (to the left). This lessens the pressure.

Testing Bobbin Tension: The Bobbin Drop Test

This test helps you see if the bobbin tension is roughly correct before you sew.

Put the bobbin into its case. Pull the thread through the tension spring slit. You should feel some drag.
Hold the bob bobbin case by the thread, letting the case hang in the air.
Give the thread a gentle tug or a little bounce.

Ideal: The bobbin case should hang for a moment, then slowly and smoothly slide down the thread a few inches with a gentle tug.
Too Loose: The bobbin case slides down the thread very easily, without you needing to tug. It might drop quickly. Turn the screw clockwise just a tiny bit.
Too Tight: The bobbin case just hangs there and does not slide down at all, even when you give it a tug. Turn the screw counter-clockwise just a tiny bit.

Do this test after each tiny adjustment of the screw. Get it to the point where it slides down slowly with a light pull.

After the drop test seems right, put the bobbin case back in the machine. Sew a test seam on your fabric scrap. Check the stitches on both sides. Is the tension balanced now?

Rule for Bobbin Tension:
* Loops on the top -> Bobbin thread too loose -> Tighten bobbin screw (clockwise).
* Fabric puckering / Thread breaking / Bottom stitch looks flat -> Bobbin thread too tight -> Loosen bobbin screw (counter-clockwise).

Adjusting bobbin tension is delicate. Make note of the screw’s starting position (maybe draw a little line on the screw and the case with a marker you can rub off) so you can go back if needed.

Finding the Right Thread Tension

Getting correct thread tension is a process of checking, adjusting, and testing. Here’s the best way to approach it:

Start with the Basics: Always, always, always check your threading, needle, bobbin winding, and cleanliness first. Most sewing machine tension problems are solved here.
Use a Test Scrap: Always test on two layers of the same fabric you are sewing, with the same threads. What works on one fabric might not work on another.
Begin with the Upper Tension: Set the sewing machine tension dial to the middle number. Sew a test. Adjust the dial based on what you see (loops on bottom = raise number, loops on top/puckering = lower number). Make small changes.
Adjust Bobbin Tension Sparingly: Only adjust the bobbin case tension screw if adjusting the top tension dial doesn’t fix loops on the top of the fabric, or if your machine manual suggests it for special threads. Use the bobbin drop test and make tiny turns of the screw.
Test After Every Change: Sew a line of stitches on your test fabric after each tension adjustment (top dial or bobbin screw). Look at the stitches on both sides.
Aim for a Balanced Stitch: You want the top and bottom threads to meet right in the middle of the fabric layers. The stitches should look neat and the fabric should lie flat.

Tips for Tricky Sewing

Different Fabrics: Thick fabrics sometimes need slightly more tension. Thin or delicate fabrics might need less tension to avoid puckering (tight stitches sewing machine). Stretch fabrics can also be tricky and may need slightly loosened tension and the right needle (ballpoint or stretch).
Different Threads: Thicker threads need less tension than thinner threads because they take up more space. If using a special thread (like metallic or thick topstitching thread), you might need to loosen the top tension a lot and maybe use a special needle.
Walking Foot: If you are sewing tricky fabrics like knits or slippery materials, a walking foot can help feed the fabric evenly. This can improve stitch quality and make tension adjustments easier.
Needle Plate: Make sure the hole in your needle plate is not damaged or rough. This can snag thread and affect tension.
Practice: Getting correct thread tension takes practice. Don’t be afraid to sew lots of test lines on scraps. Keep a small notebook with fabric type, thread type, and tension settings that worked for you.

Tables to Help

Here is a simple guide for common loop problems:

Where are the Loops?	Which Thread is Too Loose?	What to Adjust FIRST?	How to Adjust FIRST?
On the bottom of fabric	Top Thread	`Upper thread tension` dial	Increase the dial number
On the top of fabric	Bobbin Thread	`Upper thread tension` dial (try this first!)	Decrease the dial number
(If decreasing top dial doesn’t help)	Bobbin Thread	`Bobbin case tension` screw	Tighten the bobbin screw (clockwise)

Here is a simple guide for tight stitches/puckering:

Problem	What it Looks Like	Likely Cause(s)	What to Adjust	How to Adjust
`Tight stitches sewing machine`	Fabric is pulled or puckered	Top or bobbin tension too tight	`Upper thread tension` dial	Decrease the dial number
`Tight stitches sewing machine`	Still puckering after lowering top tension	Bobbin tension likely too tight	`Bobbin case tension` screw	Loosen the bobbin screw (counter-clockwise)
Thread breaks often	Thread snaps during sewing	Tension too tight (top or bottom)	`Upper thread tension` dial	Decrease the dial number

FAQ: Your Tension Questions Answered

Q: Why do I keep getting loops on the bottom of my fabric?
A: This is almost always because your top thread tension is too loose. Check that you threaded the machine correctly with the presser foot up. Then, increase the number on your sewing machine tension dial slightly until the loops stop.

Q: Why do I get loops on the top of my fabric?
A: This means your bottom thread (bobbin) is too loose, or your top thread is too tight. First, check your bobbin winding and how the bobbin is placed in the case. Make sure the bobbin thread is correctly pulled through the bobbin case tension spring. Try lowering your upper thread tension dial number. If the loops are still there and you have a front-load bobbin case, you might need to slightly tighten the bobbin case tension screw.

Q: Can I just adjust the sewing machine tension dial and fix everything?
A: The dial is the most common adjustment, but it won’t fix problems caused by wrong threading, a bad needle, or lint. Always do the basic checks first before touching the dial.

Q: How do I know what the correct thread tension looks like?
A: Sew a test seam. Look at the top and bottom stitches. They should look the same. The point where the top and bottom threads meet should be hidden inside the layers of fabric, not sitting on the top or bottom surface. The fabric should not be puckered or loose.

Q: How often should I clean my sewing machine to help with tension?
A: Clean your machine often! Especially after sewing fabrics that produce a lot of lint, like cotton or flannel. A quick clean around the bobbin area after each project, or even every few hours of sewing, can prevent many sewing machine tension problems.

Q: Should the top and bottom thread tension numbers match?
A: No, the numbers on the dial only control the top tension. There is no matching number for the bobbin tension screw. You balance them by looking at your stitches on the fabric, not by matching numbers.

Q: I adjusted the bobbin screw and now my tension is worse. What should I do?
A: If you have a front-load bobbin case, hopefully, you made a note of where the screw started. Try to turn the screw back to its original position. Remember, tiny turns make a big difference. If you feel lost, you might need to take the bobbin case to a sewing machine shop to have them set the bobbin case tension back to standard.

Q: My machine makes a knot of thread under the fabric at the start of sewing. Is that a tension problem?
A: This is often related to tension, but the fix is simple. It’s usually caused by not holding onto the thread tails (both top and bobbin) when you start sewing a seam. Hold them lightly behind the presser foot for the first few stitches. This prevents the top thread from being pulled into the bobbin area before the stitch can form.

Conclusion

Getting the correct thread tension is vital for sewing well. It makes your seams strong and your projects look neat and professional. While sewing machine tension problems can be frustrating, most issues can be fixed.

Remember to always start by checking the simple things first: your thread, needle, threading path, bobbin, and machine cleanliness. These are the most common culprits. If those are all correct, then you can move to adjusting the upper thread tension using the sewing machine tension dial. Make small changes and test often.

Adjusting the bobbin case tension is usually the last step for troubleshooting sewing machine tension. Do it carefully with tiny turns of the screw.

With a little practice and patience, you will learn to read your stitches and know exactly what adjustments your machine needs. Soon, you will be sewing with perfectly balanced tension!