Why does my thread keep twisting and knotting when I hand sew?

Thread twists because you are adding twist to it with every stitch. Four habits that stop it, and the one that fixes a thread that has already gone.

Difficulty: beginner
Time: 10 min
Read: 5 min

Short answer

Let the needle and thread dangle free every ten or twelve stitches so the accumulated twist unwinds itself. Keep the thread no longer than elbow to fingertip, thread the end that came off the reel first, and run it through beeswax or a thread conditioner. Those four between them stop nearly all of it.

Everyone assumes tangling is bad luck or bad thread. It is neither. Sewing thread is spun, which means it has twist in it, and every time you pull a stitch through you rotate the needle very slightly and add a little more. After a few dozen stitches the thread has so much twist it starts to fold back on itself, and the fold becomes a knot. Knowing that, the remedies are obvious.

Step by step

Let the thread hang and unwind.Every ten or twelve stitches, hold the work up and let the needle dangle on the thread. It will spin as the accumulated twist releases. Give it a few seconds, then carry on. This one habit removes most of the problem.
Keep the thread short.No longer than from your fingertips to your elbow, about 45cm. Longer thread accumulates more twist, abrades more as it passes through the fabric hundreds of times, and has more length in which to fold on itself.
Thread the end that came off the reel.Cut the thread and put the cut end — the end nearest the reel — through the needle eye. Thread has a direction to its spin, and sewing with it running the other way encourages tangling. Knot the end that was further along the thread.
Cut at an angle with sharp scissors.A clean diagonal cut goes through the eye easily. A frayed end from blunt scissors splits, and split thread catches on itself and on the fabric.
Condition the thread.Run it across a block of beeswax or a silicone thread conditioner, then press it briefly between the layers of a folded cloth with a warm iron so the wax is absorbed rather than sitting on the surface. Conditioned thread is smoother, resists twisting, and slides through fabric with much less friction.
Do not pull the stitch too far.Pull the thread through until the stitch is seated and stop. Continuing to pull drags the whole remaining length through the fabric again, which abrades it and adds twist.
Stop and undo a knot rather than pulling it.A loop that has formed will tighten into a hard knot if pulled. Slide a pin or the needle point into the loop and open it out. Pulling a formed knot through the fabric damages both the thread and the cloth.
Check the thread itself.Very old thread goes brittle and shreds. Cheap thread is unevenly spun and fluffs. If you have done everything on this list and it still misbehaves, replace the reel before blaming yourself.

Tips

Sewing with the thread doubled roughly doubles the tangling, because the two strands twist round each other as well. Use single thread and go over a seam twice if you need strength.
A needle threader and a good light remove most of the frustration people associate with hand sewing, and both are inexpensive.
If you are left-handed and every description feels backwards, the direction convention is the only thing that changes. The twist behaviour is identical.
Old wooden reels and modern plastic ones both hold thread that has been under tension for years. Thread bought in the 1980s is not worth using on anything you care about.

Common mistakes

Using a very long thread to avoid rethreading — It is a false economy — long thread abrades, tangles and knots so much more that it costs time rather than saving it, and the last third is usually too worn to use.
Pulling a knot tight to get it through the fabric — It cuts into the thread, weakens it at that point, and drags a hard lump through the cloth which can distort or mark it.
Waxing without heat-setting — Loose wax on the surface transfers onto the fabric and attracts dirt. Pressing it in with a warm iron between cloth fixes that.

If it doesn't work

The thread coils into loops as you sew

Cause: Accumulated twist — Fix: Let the needle hang free and spin until the twist unwinds, and do it routinely every dozen stitches thereafter.

A knot forms right at the needle every few stitches

Cause: Thread too long, or unconditioned — Fix: Cut the thread back to elbow length and run it through beeswax before rethreading.

The thread fluffs and shreds as it goes through the fabric

Cause: Poor or old thread, or too fine a needle for it — Fix: Change to a fresh reel of good polyester or cotton thread, and use a needle whose eye the thread passes through without force.

The thread keeps pulling out of the needle

Cause: Too short a tail, or too large an eye for the thread — Fix: Leave a 10cm tail, and use a needle sized to the thread. A knot in the short tail is not the answer — it makes threading the next stitch worse.

Questions people ask

Should I sew with the thread doubled?

Only when you need the extra strength — sewing on a button on a coat, for example. Doubled thread tangles far more and is harder to bury when fastening off. For most sewing, single thread over two passes is better.

Does beeswax really make a difference?

Yes, a noticeable one, particularly on hand quilting and on anything that passes through many layers. Press the waxed thread between cloth with a warm iron so the wax soaks in rather than sitting on the surface.

Why does one end of the thread behave differently?

Thread is spun with a direction. Threading the end that came off the reel and knotting the far end means you are sewing with the twist rather than against it, which measurably reduces tangling.