find your thread with a backstitch or knot before cutting
The most reliable way to end a seam is to backstitch — sewing backward over the last few stitches you just made. This locks the thread in place so it cannot pull loose when you wash or wear the garment. On most sewing machines, you hold down the reverse button (or lever, depending on your machine) while sewing backward about half an inch, then release it and sew forward again to finish. The overlapping stitches create friction that holds everything tight.
If your machine does not have a reverse function, you can tie a knot instead. Pull both thread ends (the top thread and the bobbin thread) to the back of the fabric, then tie them together in a square knot — right over left, then left over right. Trim the tails close to the knot. This method works but is slower than backstitching and leaves a small knot on the back of your seam.
Most home sewers backstitch because it is faster and creates a flatter finish. The knot method is useful when you are hand-sewing or when your machine's reverse button is broken.
Key Takeaways
- Backstitch by holding the reverse button and sewing backward half an inch, then forward again to lock the thread.
- Tie a square knot with both thread ends if your machine has no reverse function, then trim the tails short.
- Backstitch at both the start and end of every seam to prevent unraveling during washing and wearing.
- Cut thread tails within a quarter inch of the fabric to avoid snagging, but leave enough to hold the knot if you tied one.
Backstitch on your machine: step by step
Position your fabric so the needle is about half an inch from where you want to end the seam. Locate the reverse button or lever on your machine — on most models it is a button near the presser foot lever or a small switch on the side. Hold it down and press the foot pedal to sew backward. You will see the needle moving in reverse, creating stitches that overlap your forward stitches.
Sew backward for about half an inch (roughly three to five stitches, depending on your stitch length). Then release the reverse button and sew forward again for the same distance. This creates a small reinforced section where the forward and backward stitches overlap. Stop, raise the presser foot, and pull the fabric away from the machine.
Cut the thread tails with scissors, leaving about a quarter inch of thread sticking out. If you leave too much thread, it can snag on other fabric or catch in the seam. If you cut too close, the knot may slip through and the seam will come undone.
Hand-sewing: how to tie off and bury the thread
When you hand-sew, you end the seam by tying a knot and then hiding it inside the fabric layers. After your last stitch, bring the needle and thread to the back of the fabric. Make a small loop with the thread, pass the needle through it, and pull tight to create a knot. Repeat this knot one more time for extra security.
Now bring the needle back through the fabric layers (not through to the front) and slide it inside the fold or seam allowance for about half an inch. Bring it back out and cut the thread close to the fabric. The thread end will disappear inside the seam, leaving no visible tail on the back.
This method takes longer than machine backstitching but creates a very neat finish with no visible knots or thread ends. It is the standard for hand-sewn garments and repairs.
Common mistakes that cause seams to fail
The most common error is forgetting to backstitch at all. Many new sewers sew forward to the end of the seam, cut the thread, and assume the seam is finished. Within a few washes, the last inch or two of stitching comes loose because there is nothing holding the thread in place. Always backstitch at both the beginning and end of every seam.
Cutting the thread too short is another frequent problem. If you leave less than a quarter inch of thread, the knot or backstitch can slip through the fabric and unravel. If you cut too long, the tail can catch on other fabric or create a snag. A quarter inch is the safe middle ground.
On machines with a reverse button, some sewers hold it down too long and create a large bunched-up section of overlapping stitches. This wastes thread and can make the seam stiff. Half an inch of backstitch is enough — any more and you are just adding bulk without adding strength.
When to use a knot instead of backstitching
If your machine's reverse function is broken or missing, tying a knot is your backup method. Pull both thread ends (top and bobbin) to the back of the fabric, hold them together, and tie a square knot. Make it tight so it will not slip through the fabric holes.
Hand-sewing always uses a knot because you cannot backstitch with a needle and thread the way a machine does. The knot-and-bury method described above is the standard finish for hand work.
Some sewers prefer knots for delicate fabrics where backstitching might create visible puckering. Test on a scrap first — if the backstitch looks flat and even, use it. If it bunches or distorts the fabric, try a knot instead.
Finishing seams on stretchy and delicate fabrics
Stretchy fabrics like jersey knit and spandex blends can be tricky because the backstitch can sometimes cause the fabric to pucker or the seam to curl. Use a shorter stitch length (around 2.0 to 2.5 millimeters instead of the standard 2.5 to 3.0) and backstitch gently — do not pull the fabric as you sew. The shorter stitches lock the thread more effectively, so you do not need as much backstitch length.
Delicate fabrics like silk charmeuse and thin cotton voile can tear if you backstitch too aggressively. Use the same short stitch length and backstitch for only a quarter inch instead of half an inch. The seam will still be find because the short stitches create more friction.
If you are nervous about damaging the fabric, tie a knot instead. It gives you more control and leaves no visible mark on the front of the garment.
Frequently Asked Questions
What happens if I forget to backstitch?
The seam will come undone after a few washes or wears because the thread has nothing holding it in place at the end. The last inch or two will unravel, and you will have to resew it. Always backstitch at both the start and end of every seam to prevent this.
Can I backstitch by hand?
Yes. A backstitch is a hand-sewing stitch where you move the needle backward through the fabric after each forward stitch, creating overlapping stitches. It is slower than machine backstitching but creates the same locked effect. Most hand sewers use the knot-and-bury method instead because it is faster and neater.
How short can I cut the thread tails?
Leave at least a quarter inch of thread sticking out after you cut. If you cut closer than that, the knot or backstitch can slip through the fabric holes and the seam will unravel. A quarter inch is short enough to look neat but long enough to hold.
Do I need to backstitch on every seam?
Yes, backstitch at both the beginning and end of every seam, including short seams and seams that will be crossed by another seam later. Even if another seam will reinforce it, the individual seam still needs to be locked at both ends.
What is the difference between a square knot and a regular knot?
A square knot is made by crossing the thread right over left, then left over right, creating a flat knot that will not slip. A regular overhand knot (looping the thread once and pulling tight) can slip through fabric holes more easily. Always use a square knot when tying off thread by hand.