End your stitches with a backstitch or knot to lock the thread in place
A sewing machine stitch unravels when you cut the thread without securing it. The two most reliable ways to lock a stitch are a backstitch (the easiest method on most machines) and a knot (the strongest finish for hand-sewn seams). A backstitch takes two or three stitches backward at the end of your seam; a knot ties the top and bottom threads together by hand after you remove the fabric.
Which method you choose depends on your machine type, the fabric weight, and whether the seam will take stress. A backstitch works on any sewing machine and takes five seconds. A knot is slower but creates a more permanent lock and is the standard finish in tailoring and repair work.
Key Takeaways
- A backstitch — stitching backward for two or three stitches — is the fastest way to lock a stitch on a sewing machine and works on all machines.
- A hand-tied knot between the top and bottom threads is stronger than a backstitch and is the preferred finish for seams that will see heavy wear.
- Cutting threads too short or without securing them first causes seams to come apart within days or weeks of wear.
- Some machines have a dedicated backstitch button; others require you to hold the reverse lever or press a reverse key while sewing backward.
How to backstitch on a sewing machine
A backstitch is the standard finish on a sewing machine. When you reach the end of your seam, stop with the needle down in the fabric. Locate your machine's reverse control — this is usually a button labeled with a backward arrow, a lever on the side of the presser foot, or a key on the control panel. Check your machine's manual if you are unsure.
Hold the reverse control and sew backward for two or three stitches. The needle will move in reverse, locking the thread. Then release the reverse control, sew forward one stitch to align the needle, and stop. Raise the presser foot, pull the fabric away from the needle, and cut the threads about half an inch from the fabric. The backstitch holds the seam in place.
On machines without a reverse button, you may need to turn a dial or press a key before you begin sewing. Consult your manual to find the reverse function on your specific model. Some older machines have no reverse at all; in those cases, use a hand-tied knot instead.
How to tie a knot to find your thread
A hand-tied knot is stronger than a backstitch and is the finish used in tailoring, mending, and any seam that will take hard wear. After you finish sewing, raise the presser foot and pull the fabric away from the needle. Cut the top thread about six inches from the fabric, leaving the needle threaded.
Pull the fabric away from the machine to create slack in the bottom thread. Reach under the fabric and pull the bottom thread up through the top layer until you see a loop of bottom thread on top of the fabric. Insert the needle through the loop, then pull both threads tight. The two threads will knot together on the underside of the seam.
Trim both threads close to the knot. This knot will not come undone with washing or wear. It takes longer than a backstitch but is worth the time for seams on garments, bags, or anything that will be used hard.
Why unsecured stitches fail
Thread is held in a stitch by tension — the top thread and bottom thread lock around the fabric fibers. When you cut the thread without securing it, you break that lock. The loose end of the top thread pulls free, and the bottom thread follows. A single pulled thread can unravel an entire seam in minutes.
Unsecured stitches fail fastest in seams under stress — armholes, crotch seams, bag handles, and any seam that flexes or bears weight. A backstitch or knot redirects the thread tension so that pulling on one end does not unravel the whole seam. Without one, even a well-sewn seam will come apart within days of wear.
When to use a backstitch versus a knot
Use a backstitch for everyday sewing — garment seams, quilting, home décor, and anything that will not take extreme stress. It is fast, reliable, and holds for years in normal wear. A backstitch is also the standard finish in commercial sewing and is what most sewers expect to see.
Use a hand-tied knot for seams that will take hard wear: bag handles, repair work, seams on children's clothes, and any stitch you want to be absolutely certain will not fail. A knot is also the better choice if you are sewing with delicate or slippery thread that tends to slip through a backstitch. Knots are standard in tailoring and are the finish used by hand-sewing professionals.
Securing thread on different machine types
Most modern sewing machines have a reverse button or lever that works as described above. Computerized machines often have a dedicated button on the control panel; mechanical machines usually have a lever you hold while sewing backward. Check your manual to locate the reverse function on your machine.
Serger machines (overlock machines) do not have a reverse function. Instead, tie a knot by hand or use a serger-specific finish: pull the thread chain off the machine, insert the needle through the last loop, and pull tight. Some sewers also use a seam sealant (a liquid that hardens thread) on serger seams, though a knot is more reliable.
Vintage or industrial machines may not have reverse. If your machine has no reverse button, use a hand-tied knot every time. This is also the safest option if you are unsure how to use your machine's reverse function.
Common mistakes that weaken the finish
Cutting threads too short is the most common error. If you cut the thread flush with the fabric, there is nothing to hold the knot or backstitch in place. Always leave at least a quarter inch of thread above the fabric before tying a knot, and half an inch before cutting after a backstitch.
Backstitching only once is not enough. A single backstitch can slip. Always backstitch at least twice — three stitches is better. The more stitches you reverse, the more thread is locked in place.
Pulling the fabric too hard while backstitching can bend the needle or break the thread. Let the machine do the work. Hold the fabric gently and let the feed dogs move it backward.
Frequently Asked Questions
Can I use thread sealant instead of a backstitch or knot?
Thread sealant (a liquid that hardens around the thread) works as a backup but is not a substitute for a backstitch or knot. Sealant can flake off with washing or wear, and it is difficult to remove if you need to unpick the seam. Use sealant only on seams you are certain you will never need to alter.
What if my machine has no reverse button?
Tie a hand knot every time. Pull the bottom thread up through the top layer of fabric, insert the needle through the loop, and pull both threads tight. This works on any machine and is actually stronger than a backstitch.
Do I need to backstitch at the beginning of a seam too?
Yes. Backstitch two or three stitches at the start of every seam, then sew forward. This locks the thread at both ends and prevents the seam from unraveling from either direction.
How short can I cut the thread after a backstitch?
Leave at least half an inch of thread above the fabric. Cutting closer risks the backstitch slipping free. A quarter inch is the absolute minimum; more is safer.
Is a knot visible on the finished garment?
A hand-tied knot sits on the underside of the seam and is not visible on the right side of the fabric. It may create a small bump on the wrong side, but this is normal and expected in tailored garments.