What Double Stitching Does and When to Use It
Double stitching means working two rows or passes of stitches in the same location, creating a thicker, more durable line. In knitting, this reinforces seams where stress concentrates — armholes, necklines, the base of ribbing — and prevents runs from spreading if a single thread breaks. It also adds visual definition to edges and can tighten loose tension in a finished piece.
You use double stitching most often when seaming two pieces together with a tapestry needle, though you can also work it directly into live stitches before binding off. The second pass follows the exact path of the first, locking the thread in place and doubling the thread count in that line.
Double stitching takes extra yarn and time, so you do not need it everywhere. Reserve it for high-wear zones: underarms, where sleeves meet the body, and edges that will see frequent handling or stretching.
Key Takeaways
- Double stitching reinforces seams by running a second pass of thread through the same stitch path, doubling the thread in that line.
- The most common method uses a tapestry needle to work the seam twice in succession, following the same path both times.
- You can also work double stitches directly into live stitches before binding off, using your working yarn and needles.
- Double stitching works best on high-stress areas like armholes, necklines, and seams that will stretch or bear weight.
- The technique requires only a tapestry needle and your existing yarn; no special tools or materials are needed.
Double Stitching a Seam with a Tapestry Needle
This is the most straightforward method. After you have seamed two pieces together using mattress stitch, backstitch, or whip stitch, thread your tapestry needle with the same yarn and follow the exact same path a second time. Start at one end of the seam and work stitch for stitch along the line you just created.
The second pass should sit directly on top of the first. If your first seam went under one stitch and over the next, your second pass does the same. This locks the original thread in place and fills the seam line with double the yarn, making it much harder to pull apart or ladder if a thread breaks.
Work slowly on the second pass so you do not miss any stitches. If the seam is long, you can break it into sections — seam the armhole, double stitch the armhole, then move to the next section. This prevents the needle from getting tangled in a long length of thread.
Double Stitching Before You Bind Off
If you want to reinforce an edge before binding off — such as a neckline that will receive a collar or a buttonhole band — you can work double stitches directly into the live stitches on your needle. This method works best on edges where you have not yet bound off.
Knit across the row normally, then knit the same row again without turning your work. You are working into the same stitches twice. This creates a doubled stitch column that sits on top of the original row. When you bind off, you bind off through both layers, locking them together.
This approach is faster than seaming and double stitching afterward, but it only works if you catch the edge before binding off. Once stitches are cast off, you cannot go back and add this reinforcement without picking up stitches again.
Double Stitching with Backstitch for Seams
If you seamed your pieces with backstitch instead of mattress stitch, the double stitch process is the same: thread your needle and follow the exact path of the first seam. Backstitch creates a very tight seam, so the second pass will sit snugly against the first and create a dense, reinforced line.
Backstitch seams are already quite strong, so double stitching them is optional unless the seam will bear significant weight or stretch. Armholes and underarms on fitted garments benefit most from this reinforcement.
Choosing Yarn Weight and Needle Size for Double Stitching
Use the same yarn you used to knit the garment when you double stitch. If your yarn is very thick or your seam is already tight, you may need to split the yarn — use only half the strands if you are working with a multi-ply yarn. This prevents the seam from becoming so thick that it creates a visible ridge or makes the fabric stiff.
Your tapestry needle should be large enough to pass through the stitches without splitting the yarn, but not so large that it stretches the stitch openings. A needle one size up from what you used to knit is usually right. If the needle keeps snagging, try a blunt needle instead of a sharp one.
Common Mistakes and How to Avoid Them
The most common error is not following the exact same path on the second pass. If your first seam went under a stitch, your second pass must also go under that same stitch. Deviating creates an uneven, lumpy seam that does not reinforce properly. Mark your path with a stitch marker or a piece of contrasting thread if the seam is long.
Another mistake is pulling the thread too tight on the second pass. This can pucker the seam or distort the stitches. Keep the tension the same as your first pass — firm enough to hold the pieces together, but loose enough that the seam lies flat.
Do not double stitch the entire garment. This wastes yarn and time and makes the fabric stiff. Limit double stitching to seams that will see stress: underarms, shoulder seams, and necklines. Seams on the sides or sleeves usually do not need it.
When Double Stitching Is Not Necessary
Garments made from sturdy yarn — wool, cotton, or blends — usually hold up well with a single, properly executed seam. Double stitching becomes more important with delicate or slippery yarns like silk, linen, or very fine merino, where a single thread can slip or break more easily.
If your seam is already very tight and find, double stitching adds bulk without much benefit. Test your seam by gently pulling on it. If it does not move or stretch, a second pass is optional. If it feels loose or you can see gaps between the stitches, double stitching will help.
Frequently Asked Questions
Do I have to double stitch every seam?
No. Double stitch only the seams that will see the most stress: underarms, where sleeves meet the body, and necklines. Side seams and sleeve seams usually do not need reinforcement unless you are using very delicate yarn or the garment will be worn frequently.
Can I double stitch with a different yarn color?
You can, but it will be visible on the inside of the garment. Use the same yarn color as your seam for a clean, invisible finish. If you want to hide the double stitch, work it on the inside of the garment where it will not show.
What if I double stitch and the seam still feels loose?
Your tension may be too loose on both passes. Try again, pulling the thread slightly tighter — not so tight that you pucker the seam, but firm enough that the stitches sit snugly together. If the problem persists, your original seam may have skipped stitches; check that you followed the correct path on both passes.
Does double stitching make the seam visible from the outside?
No, if you work it correctly on the inside of the garment. The double stitch reinforces the seam without changing how it looks from the outside. Work on the inside surface of the seam, and the outside will remain smooth and invisible.
Can I double stitch a seam I finished weeks ago?
Yes. Thread your tapestry needle and follow the original seam path. You can reinforce any finished seam at any time. This is useful if a seam starts to show wear or if you realize after wearing the garment that a particular seam needs more strength.