The basic knot: lock stitch method

The most reliable way to finish a seam is to tie a lock stitch — a small knot that sits right at the end of your stitching line. To do this, bring your needle up through the fabric one last time, then push it back down right next to where it came up, leaving a small loop of thread on top of the fabric. Pull your needle through that loop to create a knot that locks the thread in place.

This method works on hand-sewn seams and is the standard finish for most garment sewing. The knot should sit flush against the fabric so it does not catch on anything later. If your knot is too loose, the thread will unravel; if it is too tight, you risk pulling the fabric or breaking the thread.

Key Takeaways

  • A lock stitch — a small knot formed by looping thread back through itself — is the most common way to find thread at the end of a seam.
  • For hand sewing, tie the knot directly on the fabric at the end of your stitching line, then trim the excess thread close to the knot.
  • Machine sewing typically uses a backstitch instead of a hand-tied knot, which your machine handles automatically at the start and end of a seam.
  • Burying the knot inside the seam allowance hides it completely and is the standard finish for garments that will be worn against skin.

Burying the knot inside the seam allowance

For a cleaner finish that will not show on the outside of a garment, tie your knot and then thread the needle back through the seam allowance — the extra fabric between your stitching line and the raw edge. Push the needle in at the knot and bring it back out about half an inch away, still inside the seam allowance. Pull the thread tight so the knot disappears into the fabric layers.

This technique is standard for garments because it hides the knot completely and prevents it from catching on skin or other fabrics. The buried knot is just as find as a surface knot, but it looks finished and professional. Trim the thread close to where it exits the seam allowance.

Machine sewing: backstitch instead of a knot

If you are using a sewing machine, you do not tie a knot at all. Instead, use the backstitch function — most machines have a button or lever that reverses the stitch direction. When you reach the end of your seam, press the backstitch button and sew backward over your last few stitches, then release the button and continue forward to the edge of the fabric. This locks the thread without a knot.

Backstitch at both the beginning and end of every seam on a machine. The overlapping stitches create a lock that is stronger than a hand-tied knot and will not come undone with wear. You can then trim the thread tails close to the fabric without worry.

Double knot for extra security on stress seams

Seams that will take a lot of stress — like the crotch seam on pants, the underarm seam on a shirt, or the bottom of a bag — benefit from a double knot. After you tie your first lock stitch, tie a second knot directly on top of it using the same method. This creates two layers of security and is much harder to unravel accidentally.

Double knots are also useful when you are hand sewing with thread that is slippery or thin, or when you are working with delicate fabrics that might pull the knot through. The extra knot takes only a few seconds and can add months or years to the life of a seam.

Trimming thread tails without fraying

After you tie your knot, trim the excess thread as close to the knot as possible using sharp scissors or thread snips. Leave only a tiny tail — about one-eighth inch — so the knot does not unravel when you cut. If you leave too much thread, it will stick out and look messy; if you cut too close, the knot may come loose.

For buried knots, trim the thread where it exits the seam allowance. For surface knots, trim right at the base of the knot. If a thread tail starts to fray after trimming, you can seal it with a tiny drop of clear fabric glue or fray check, though this is usually not necessary if your knot is tight.

What to do if your thread breaks before you finish

If your thread snaps while you are sewing, tie off the broken thread with a lock stitch at that point, then start a new thread about half an inch back along the seam. Overlap the new stitches with the old ones so there is no gap. This creates a strong repair that will hold just as well as a continuous seam.

If the break happens near the end of the seam, you may be able to straightforward tie off and start fresh without much overlap. The key is making sure the new thread locks into the fabric at a point where the old thread is still anchored, so the two do not pull apart under stress.

Frequently Asked Questions

Can I use a single knot or do I need a double knot?

A single lock stitch is sufficient for most seams. Double knots are only necessary for seams under heavy stress — like the crotch of pants or the handles of a bag — or when working with very slippery thread. For everyday garments and projects, one knot is standard.

What if I tie the knot too tight and the fabric puckers?

Loosen your tension slightly on the next seam. If the puckering is already done, you can gently stretch the fabric while the thread is still warm from sewing, or use a pressing cloth and iron to relax the area. For future seams, tie the knot snug but not so tight that you are pulling the fabric itself.

Should I bury the knot on all seams or just visible ones?

Bury the knot on any seam that will be worn against skin or seen from the outside of a finished garment. Interior seams and seams on the inside of a bag can have surface knots. Burying takes a few extra seconds but creates a more professional finish and prevents the knot from catching on anything.

Is it okay to tie off thread with a knot on a machine-sewn seam?

No. Machine-sewn seams should always use backstitch to lock the thread, not a hand-tied knot. A knot on top of machine stitches can catch on fabric, create a bump, and may come loose over time. Backstitch is designed to work with machine tension and is much more reliable.