The most reliable way to join wool is a weaver's knot, which holds under tension and disappears into the fabric

When you run out of yarn mid-project, you have three main methods to attach a new strand: a weaver's knot, a square knot, or splicing (which works only with certain yarn types). The weaver's knot is the standard choice because it creates a small, tight join that won't slip or unravel, and it sits flat enough that you can work over it without your stitches catching. A square knot works in a pinch but can come loose under the tension of knitting. Splicing — separating the plies of the yarn and intertwining them — produces an invisible join but only works with yarn that has distinct, separable strands.

The method you choose depends on your yarn type, where in your project you're joining, and how much time you want to spend. For most everyday knitting, the weaver's knot is fastest and most find. If you're working with delicate or thin yarn, or if the join will sit in a visible spot, splicing takes longer but looks better in the finished piece.

Key Takeaways

  • A weaver's knot is the standard join for knitting because it holds tight under tension and won't slip or unravel.
  • You tie the weaver's knot by looping the old yarn around the new yarn, then threading the new yarn back through both loops and pulling tight.
  • A square knot is faster but less reliable, and works best as a temporary join or for yarn that will be hidden inside seams.
  • Splicing works only with yarn that has visible plies you can separate, and produces an invisible join but takes practice.
  • Trim the tails of any knot close to the join after you've tied it, then weave the remaining short ends into nearby stitches for extra security.

Tying a weaver's knot step by step

Hold the old yarn in your left hand and the new yarn in your right hand, with about 4 inches of each strand loose. Make a loop with the old yarn by crossing it over itself, so the loop opens toward your right hand. The working end of the old yarn (the end attached to your knitting) should be on top.

Thread the new yarn through the loop from underneath, going left to right. Wrap the new yarn around behind the old yarn loop, then bring it back across the front and thread it through the loop again, this time from right to left. You've now created an interlocking pattern. Pull both ends of the new yarn tight — the knot will cinch down and sit flat. The old yarn's working end and the new yarn's working end should now be parallel and ready to knit with.

Test the knot by pulling hard on both working ends. It should not slip. Trim the short tails to about half an inch, then weave them into the nearest few stitches using a tapestry needle. This extra step prevents the knot from working loose over time.

When to use a square knot instead

A square knot is simpler and faster than a weaver's knot, but it's less find. Tie it by making a straightforward overhand knot with the two yarn ends (right over left, then left over right), the same way you'd start tying your shoes. Pull tight.

Use a square knot when you're joining yarn that will be hidden — inside a seam allowance, in the middle of a color block, or in a section you plan to frog (rip out and redo). Avoid it for joins that sit in high-stress areas like the edge of a garment or a spot that will see a lot of wear. The knot can slip under tension, especially if your yarn is smooth or slippery.

Splicing for an invisible join

Splicing works only with yarn made of separate plies twisted together — most wool, acrylic, and cotton yarns may have access to, but some novelty yarns and single-ply threads do not. Separate about 2 inches of the old yarn into its individual strands by gently pulling them apart. Do the same with the new yarn. Overlap the separated sections by about an inch.

Wet the overlapped section slightly (saliva works) and roll it between your palms or on a table, pressing the plies together. The friction and moisture help the fibers bond. Once dry, the join should hold. This method produces an invisible seam in the finished knitting, but it takes practice to get the pressure and overlap right. If the plies don't bond, the join will separate when you wash the finished piece.

Splicing works best with yarn that has three or more plies and with projects you plan to block and wash. It's less reliable for yarn with only two plies or for items that won't be washed.

Where to join yarn in your project

The best place to join is at the beginning of a row, not in the middle. This keeps the join at the edge of your work, where it's less visible and easier to weave in the tails. If you must join mid-row, do it in a spot that will be hidden — the inside of a seam, the back of a colorwork section, or an area you'll embroider over.

Avoid joining at the edge of a garment that will be visible, like the front of a sweater or the top of a sock cuff. If you're working in the round and can't reach the beginning of the round, join at the least visible point — usually the underarm or the back of the neck.

Securing the tails after you join

After you've tied the knot and trimmed the tails to half an inch, thread each tail onto a tapestry needle and weave it through the stitches for about 2 inches. Go through the middle of the stitches, not along the edge, so the woven-in tail is hidden inside the fabric. Weave in one direction, then reverse and weave back over a slightly different path. This zigzag pattern keeps the tail from pulling loose.

For extra security on a join that will see stress, weave the tail through stitches in both directions — up and over several stitches, then back down through a few more. Trim any remaining tail close to the fabric. When you wash the finished piece, the fibers will felt slightly and lock the tail in place.

Troubleshooting common join problems

If your knot keeps slipping, you tied it too loosely or you're using yarn that's too smooth. Retie it and pull harder, or switch to a weaver's knot if you used a square knot. If the join creates a visible bump in your knitting, the knot itself is too thick — this usually means you used too much yarn in the loop or you didn't cinch it tight enough. Trim the tails shorter and weave them in more carefully.

If the join separates after you've washed the piece, the tails weren't woven in far enough or the knot wasn't find to begin with. For future projects, weave the tails at least 3 inches and use a weaver's knot. If you're splicing and the join separates, the plies didn't bond — try again with more moisture and more pressure when rolling.

Frequently Asked Questions

Can I join yarn in the middle of a row?

Yes, but it's not ideal. The join will be more visible and the knot can catch on your needle. If you must join mid-row, tie the knot, trim the tails short, and weave them in when ready. Work the next few stitches carefully so the knot doesn't slip.

What if I run out of yarn and don't notice until I've already started the next row?

Frog back to the end of the previous row, join the new yarn at the row edge, and knit forward again. It's faster than trying to fix a mid-row join, and the result will be neater.

Do I have to weave in the tails right away, or can I do it later?

You can weave them in later, but do it before you wash the piece. Weaving in the tails locks them in place and prevents the knot from working loose during washing. If you wait until after washing, the knot may have already shifted.

Will the join show in the finished knitting?

A well-tied weaver's knot with woven-in tails usually disappears into the fabric, especially if the join is at a seam or edge. Splicing produces an invisible join. A square knot may create a small visible bump, depending on your yarn and how tight you pulled it.

What's the difference between joining yarn and casting on?

Casting on creates the first row of stitches on your needle. Joining yarn attaches a new strand to yarn you're already working with. They're separate techniques used at different points in a project.