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Sewing Machine Tension Problems: How to Fix Them

Guide type
Troubleshooting
Last reviewed
Sources
17 cited
Tested by us
No. How we research

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Short answer

Don't touch the dial first. Brother's manual is clear: "If the upper threading and bobbin threading are incorrect, the thread tension cannot be adjusted correctly. Check the upper threading and bobbin threading first, and then adjust the thread tension."1 Rethread the top thread with the presser foot raised, so the thread goes between the tension discs, then reinsert the bobbin.2,3 If it is still wrong, read the stitches: loops on top mean the upper tension is too tight (lower the number); loops underneath mean it is too loose (raise the number).4

Check in this order

  1. Rethread the top thread with the presser foot up. Brother: “The pressure foot has to be raised so the thread can go into the tension disc.”2 BERNINA explains why: raising the foot opens the tension discs “and the thread can slide easily between them.”3
  2. Reinsert the bobbin. Brother’s troubleshooting table tells you to return the dial to “4” and redo the bobbin when the bobbin thread shows on the right side and the upper thread “appears as a straight line on the right side of the fabric.”1
  3. Check the needle and thread. A needle or thread that doesn’t suit the fabric means “the thread tension will not be adjusted correctly, causing wrinkles in the fabric or skipped stitches.”1
  4. Only then, adjust the dial, a little at a time, and sew a test line after each change, on a scrap of the same fabric.1,11

Read the stitches

What the stitches tell you
What you seeWhat it meansWhat to do
Loops on the top of the fabric; bobbin thread shows on the right sideUpper tension too tight, or the bobbin is misthreaded4,12Rethread the bobbin; then turn the dial to a lower number4
Loops on the back of the fabric; needle thread shows underneathUpper tension too loose, or the top thread is misthreaded4,13Rethread the top with the foot up; then turn the dial to a higher number4
Seam puckersToo much (or too little) tension4Check the needle and thread, then adjust the dial1,4
Dial changes nothing; top thread is a straight lineBobbin threading is wrong1Correctly install the bobbin thread1
From Brother's XM2701 manual and help pages, and JUKI's HZL-L manual. Higher number = tighter upper thread.

Brother explains the mechanism behind the first row: when the bobbin thread is misthreaded, its tension is too loose, so it gets pulled up and shows on the right side of the fabric.12

What “correct” tension looks like

The makers agree, once you separate straight stitch from zigzag and decorative stitches.

  • Straight stitch: balanced. Brother’s SE700 manual: the two threads “should cross near the center of the fabric”, with only the upper thread visible on the right side and only the bobbin thread on the wrong side.14 JUKI’s HZL-L manual: “the stitches are evenly balanced.”13 SINGER’s 4452 manual: a balanced tension is “usually only desirable for straight stitch construction sewing.”5
  • Zigzag and decorative stitches: a little top thread underneath. SINGER’s 4452 manual, for these stitches: “Correct thread tension is when a small amount of the upper thread appears on the bottom side of fabric.”5 JUKI: the needle thread “shows slightly on the wrong side”.13 Brother: “Many decorative stitches and satin stitches are designed so that the upper thread wraps to the back slightly”.15

So a little top thread under a zigzag is normal; under a straight stitch, it is a sign to adjust.

The tension discs

Test them. SINGER’s test: with the presser foot raised, pull the thread: “It should pull easily.” Lower the foot: “the thread should now resist when you pull it. … If there is no increased tension, the machine is not threaded correctly.”16

Clean them. BERNINA: “Fold a piece of thin fabric (don’t use outer edges) and pull it through the thread tension discs several times.”3 Kentucky’s guide uses plain muslin, with the presser foot raised “to release the pressure between the disks.”7

Never oil them. New Mexico State: “Do not oil the tension discs”.8

Worn discs: not a home fix. New Mexico State lists “Tension discs are worn so that thread works in a groove” among the causes of upper thread breaking.17 None of the manuals we read shows how to replace the discs; Brother’s manual says: “If the problem persists, contact your dealer or the nearest authorized service center.”4

A test for balance (Kentucky)

Kentucky’s guide suggests sewing a line on the bias, then pulling the ends of the seam until a thread breaks: if only the upper thread breaks, the upper tension is tighter than the lower; if both break, “the tensions are balanced.”11

Questions

What causes sewing machine tension issues?

Most often, threading. Brother: "If the bobbin thread was incorrectly threaded, the upper thread may be too tight. If the upper thread was incorrectly threaded, the upper thread may be too loose."4 A needle or thread that doesn't suit the fabric also stops the tension from adjusting correctly, causing wrinkles or skipped stitches.1

What is the best sewing machine tension setting?

There is no single number. Brother's CS7000X manual tells you to return the dial to "4" and then rethread the bobbin when a misthreaded bobbin shows on top, and Brother's help pages say "between 4-5" for many dial models.1,2 SINGER's 4452 manual gives "4" as its basic setting, and SINGER says the range from 3 to 5 is normal for most regular sewing thread on its Heavy Duty 6800C.5,6 Then adjust by looking at the stitches.

What are tension discs?

The two discs the upper thread passes between; they press on the thread to set its tension. Raising the presser foot opens them: SINGER: "You must raise the presser foot to release the tension discs."5 That is why you thread with the foot up.

How do I clean the tension discs?

With the presser foot raised, slide a folded piece of thin fabric between the discs several times, as BERNINA and Kentucky's extension guide describe.3,7 Never oil them: "Do not oil the tension discs" (New Mexico State).8

SINGER Heavy Duty tension problems: what should I check?

First the thread and the bobbin. SINGER doesn't recommend threads larger than size #69 (Tex 70), waxed or coated threads, or hand quilting thread on its Heavy Duty 6800C, and says all its Heavy Duty models use the same Class 15 bobbin.6,9 Then use SINGER's test: foot up, the thread pulls freely; foot down, you should feel resistance.10

Bottom line

Fix tension in this order: rethread the top with the foot up, reinsert the bobbin, check the needle and thread, and only then turn the dial, a little at a time, while reading the loops. If the tension still won't change, clean the discs; worn discs are not a home fix.

Related guides

What we checked, and what we didn't

Checked
  • Tension symptoms, causes and remedies in Brother, JUKI, SINGER and BERNINA manuals and help pages
  • Tension disc checks and cleaning in SINGER's help center, BERNINA's manual and two university extension guides
Not checked
  • How these steps work on your machine: we have not tested them; your manual comes first
  • Dial numbers are not comparable between brands: a 4 on one machine is not a 4 on another

Sources

  1. Operation Manual 888-N00 family (CS7000X) · Brother
  2. Tension will not set on the sewing machine · Brother USA help
  3. BERNINA 335 User Manual (2025) · BERNINA
  4. Operation Manual 885/888-X06 family (XM2701) · Brother
  5. Instruction Manual 4443 / 4452 · SINGER
  6. SINGER Heavy Duty 6800C Troubleshooting Tips · SINGER help center
  7. CT-MMB-205: Preventive Machine Maintenance, Problems, and Possible Causes (2005) · University of Kentucky Cooperative Extension
  8. Guide C-102: Sewing Machine Maintenance (2017) · New Mexico State University Extension
  9. Heavy Duty 8832 · SINGER help center
  10. Instruction Manual HD4552 · SINGER
  11. CT-MMB-213: Adjusting Sewing Machine Tension · University of Kentucky Cooperative Extension
  12. Help answer 151460 (thread tension, SE700 family) · Brother USA help
  13. HZL-L series Instruction Manual · JUKI
  14. SE700 Sewing and Embroidery Machine Operation Manual (888-P10) · Brother
  15. Operation Manual 888p5x: Thread Tension · Brother support
  16. Singer Machine FAQs · SINGER help center
  17. Guide C-202: Checklist of Common Sewing Machine Problems (2016) · New Mexico State University Extension

Revision history

2026-11-10First version.