Why Is My Tension Off? Fixing Skipped Stitches and Loops

Quick Answer

Match the fix to the symptom before you touch a dial. Loops on the underside almost always mean the top thread is too loose or not seated in the tension discs, while skipped stitches usually point to a needle, threading, or fabric-support problem rather than tension. Re-thread with the presser foot up, fit a fresh needle for the fabric, clean the bobbin area, then test on a scrap. Adjust the top tension in small steps only after those checks fail.

Loops vs. Skips: Two Different Problems, Two Different Fixes

A loop is a thread-delivery problem. The needle thread is not being held back consistently, so excess thread gets pulled under the fabric and tangles. Skipped stitches are a stitch-formation problem: the needle fails to pick up the bobbin thread on some stitches, leaving gaps or a dotted line. Treating both as 'tension' is why so many sewists turn the dial back and forth for an hour with no result.

Before adjusting anything, sew a test seam on the fabric you are actually using, with the same thread in the needle and bobbin. A machine that stitches perfectly on cotton can loop on stretch fabric and skip on vinyl, so your test has to match the real job.

• Loops underneath: suspect top threading, tension discs, or bobbin winding.
• Loops on top: suspect bobbin threading or bobbin tension.
• Skipped stitches: suspect the needle, the fabric, or the machine's timing.
• Snapped or shredded thread: suspect the needle, thread path, or a burr.

Check the Top Thread Path Before You Adjust Anything

Raise the presser foot and re-thread from the spool. With the foot down, the tension discs close and grip the thread; with it up, they open. If you thread while the foot is down, the thread can sit outside the discs, which produces instant looping no matter where the dial is set. Pull the thread at the needle after threading: you should feel steady resistance, not a free slide.

Confirm the thread is fully seated in every guide, the take-up lever, and the needle bar guide. A thread that missed one guide can look correctly threaded from the front and still loop underneath.

Bobbin Tension Troubleshooting Without Guesswork

Remove the bobbin case and check for lint, bent springs, or a bobbin wound unevenly. An overfilled or cross-wound bobbin changes how the thread leaves the case and can mimic a tension fault. Drop the bobbin case by its thread: it should hold position with a light bounce, not fall freely or hang rigidly.

Resist the urge to turn the bobbin screw first. On most machines the bobbin tension is set at the factory and rarely needs changing; the top tension is the adjustment meant for day-to-day fabric and thread changes. If you do adjust the bobbin screw, mark its starting position so you can return to it.

Needle, Fabric, and Machine Timing: The Real Cause of Skipped Stitches

A dull, bent, or wrong-type needle is the most common reason a machine skips. A needle that is slightly bent can miss the bobbin hook entirely on some stitches. Fit a new needle of the correct size and type for the fabric, insert it fully into the clamp, and make sure the flat side faces the direction your manual specifies.

Fabric can also cause skips. Very stretchy knits, thick seams, and coated fabrics can deflect the needle or prevent the bobbin hook from catching the loop. A stabilizer, a different needle point, or slower speed often solves what tension never will. If a fresh needle, correct threading, and a clean bobbin area still skip on a plain woven fabric, the machine likely needs a timing check by a technician.

How to Adjust Thread Tension in Small, Repeatable Steps

Set the top tension to its mid-point, sew a 6-inch test seam, and look at both sides. If the bobbin thread is visible on top, the top tension is too loose; increase it one number at a time. If the needle thread is visible underneath, the top tension is too tight; decrease it one number at a time. Re-test after every change rather than making several adjustments at once.

On a balanced stitch, the threads meet inside the fabric and neither side shows the other's thread. Write down the number that works for your common fabric and thread combination so you have a known starting point next time.

When to Stop Adjusting and Change Something Else

Stop turning the dial if three consecutive small adjustments produce no change. At that point the cause is not tension, and further adjustment only adds a second problem. Switch to a different thread weight, a different needle, or a different presser foot suited to the task.

For edge finishing and overlock-style work, a dedicated foot guides the fabric edge so the machine can form stitches consistently, which removes a variable that looks like tension trouble. Similarly, when a project involves cords or piping, the right foot keeps the cord aligned so the needle and bobbin interact predictably.

Tension Diagnosis Table

• Loops on the underside: The top thread is loose or sitting outside the tension discs. Re-thread with the presser foot up, confirm the thread is in every guide, then increase top tension one step at a time. If loops persist after re-threading and two tension increases, check the bobbin case for lint or a bent spring.
• Loops on the top side: The bobbin thread is too loose or the bobbin is wound unevenly. Remove the bobbin case, clean it, and re-insert a properly wound bobbin. Only adjust the bobbin screw if a correctly wound bobbin and clean case still loop; mark the original position first.
• Skipped stitches on woven fabric: Fit a new needle of the correct size and type, inserted fully with the flat side as your manual directs. Clean the bobbin area and re-thread. If skips continue on plain woven fabric with a fresh needle, stop adjusting tension and have the machine's timing checked.
• Skipped stitches on knit, stretch, or coated fabric: The needle is likely deflecting. Switch to a needle point suited to the fabric, add stabilizer, and reduce speed. This is a fabric-support problem, not a tension problem; dial changes will not fix it.
• Thread shredding or snapping: Inspect the needle for burrs, check the thread path for rough spots, and match thread weight to needle size. Replace the needle first; it is the cheapest and most common culprit.

Tools That Remove Tension Variables

• #2A BERNINA Overlocker Foot: The BERNINA #2A Overlocker Foot is designed for overlock and edge-finishing stitches and suits a wider range of fabric weights than the standard #2. If edges fray or stitches pull unevenly on light and heavy fabrics, this foot guides the edge cleanly so you can judge whether the real issue was fabric support rather than tension.
• #59C BERNINA Double-Cord Foot 4-6mm: The #59C BERNINA Double-Cord Foot sews two parallel cords with a diameter of 4-6 mm and is made for 9 mm machines. When piping or corded seams produce loops or skipped stitches, this foot holds both cords in position so the stitch forms consistently and you can isolate whether the problem is tension or cord movement.
• BERNINA 325: The BERNINA 325 is an entry-level machine with an intuitive design and a wide stitch selection for everyday sewing, mending, and light decorative work. A machine with straightforward threading and a clear tension dial makes the re-thread-and-test routine faster, which is exactly what tension troubleshooting depends on.