Why armpit holes happen and how to repair them
Armpit holes form because that seam takes the most stress when you move your arm—the fabric stretches, the stitches break, and a small tear becomes a larger hole. You can repair this yourself with a needle, thread, and about 20 minutes, and the fix will hold through normal wear if you use the right stitch and reinforce the weak spot.
The armpit is harder to sew than a straight seam because the fabric curves and you're working in a tight space, but the technique is straightforward: you'll close the hole with a ladder stitch (which is nearly invisible) or a whip stitch (which is faster), then reinforce the repair from the inside with a patch or extra stitching so the seam doesn't tear again in the same place.
Key Takeaways
- Armpit holes need reinforcement from the inside because the seam itself is weak—a patch or extra stitching on the underside prevents the hole from reopening.
- A ladder stitch closes the hole invisibly from the outside, while a whip stitch is faster but slightly visible and works best on darker fabrics.
- Use thread that matches your shirt color and a needle small enough to pass through the fabric without leaving large holes.
- The repair takes 15 to 25 minutes and requires only a needle, thread, scissors, and optionally a small piece of fabric for reinforcement.
Gather your materials and prepare the hole
You will need a needle (size 8 or 9 works for most shirt fabrics), thread that matches your shirt color, small scissors, and optionally a scrap of lightweight fabric like cotton or linen for reinforcement. If you don't have a matching thread, a neutral color like gray or tan is less noticeable than white on most fabrics.
Lay the shirt flat on a table with the armpit facing up. If the hole has frayed edges, trim any loose threads with scissors—don't pull them. If the hole is larger than a dime, you'll want to add a patch on the inside; if it's smaller, you can close it and reinforce it with stitching alone. Turn the shirt inside out so you can see the underside of the armpit seam, then turn it right-side out again to work on the outside. This sounds backwards, but you'll do most of the work from the inside after closing the hole from the outside.
Close the hole with a ladder stitch
A ladder stitch closes a hole so the seam looks unbroken. Thread your needle and tie a knot at the end. Start by pushing the needle through the fold of fabric on one side of the hole, just inside the edge—not through both layers, but through the fold itself. This hides your starting knot inside the fabric.
Bring the needle out about 1/8 inch along the edge of the hole. Cross to the opposite side and push the needle into the fold of fabric directly across from where you came out. Slide the needle inside the fold for about 1/8 inch, then bring it back out. Return to the first side and repeat: in through the fold, slide 1/8 inch, out through the fold. As you stitch, gently pull the thread every few stitches to draw the two sides of the hole together. The hole will close as you work, and the stitches will hide inside the fold of fabric.
Continue until the hole is completely closed. Tie off the thread by making a small loop, passing the needle through it, and pulling tight. Push the needle through the fold one more time and bring it out an inch away, then trim the thread close to the fabric so the tail disappears inside.
Reinforce the repair from the inside with a patch or extra stitching
Turn the shirt inside out. The closed hole should now look like a thin line on the inside. This is where the seam was weak, so you need to reinforce it so it doesn't tear again. You have two options: add a small fabric patch or stitch over the seam multiple times.
For a patch, cut a piece of lightweight fabric (cotton, linen, or even a piece of old t-shirt) into a rectangle about 1.5 inches by 2 inches. Center it over the closed seam on the inside of the shirt. Thread your needle and use a whip stitch to sew the patch down: push the needle through the edge of the patch, then through the shirt fabric just below it, then back through the patch edge, working your way around all four sides. Space your stitches about 1/8 inch apart. This adds a reinforced layer that spreads the stress across a larger area.
If you don't have patch fabric, you can reinforce by stitching over the seam itself. Use a backstitch: push the needle through both layers of the seam, then bring it back out 1/8 inch ahead. Push the needle back through the hole you just made and come out another 1/8 inch ahead. This creates a solid line of overlapping stitches that strengthens the seam. Make two or three passes over the same line for maximum strength.
Use a whip stitch if you need a faster repair
If the hole is small and you want to skip the ladder stitch, a whip stitch is faster, though it will be slightly visible. Turn the shirt inside out and fold the raw edges of the hole inward so they meet in the middle. Pin them in place or hold them with your fingers.
Thread your needle and tie a knot. Push the needle through the fold of one side of the hole, hiding the knot inside. Bring the needle out and when ready push it back through the opposite fold, just a thread's width away. Come back out on the first side and repeat, working your way around the hole. The stitches will form a line along the seam where the hole was. This stitch is less invisible than a ladder stitch but works well on dark fabrics where the thread blends in.
Common mistakes that weaken the repair
The most common mistake is skipping the reinforcement step. Closing the hole looks finished, but the seam is still weak in that spot, and the hole will reopen the next time you raise your arm. Always add a patch or extra stitching on the inside.
Another mistake is using thread that's too thick or a needle that's too large. This creates visible holes in the fabric and weakens it further. Use the smallest needle that feels comfortable in your hand, and use regular sewing thread, not embroidery thread or yarn.
Pulling the thread too tight while stitching will pucker the fabric and create stress points. Pull just hard enough to close the hole and hold the stitches in place—the fabric should lie flat when you're done.
When to consider replacing the shirt instead
If the hole is larger than a quarter, or if the armpit seam itself is torn (not just the fabric around it), the repair may not hold. A seam repair requires removing the old stitches and re-sewing the seam, which is more involved than patching a hole. If the shirt is old or the fabric is thin and worn, a repair may only last a few washes before the area tears again.
If the armpit area has multiple small holes or the fabric feels thin and fragile, the shirt has likely reached the end of its life. A single clean hole in otherwise good fabric is worth repairing; widespread damage is not.
Frequently Asked Questions
Can I sew an armpit hole without turning the shirt inside out?
You can close the hole from the outside using a ladder stitch without turning the shirt inside out, but you must turn it inside out afterward to add reinforcement. Skipping the inside reinforcement is the main reason armpit repairs fail. The extra step takes only a few minutes and doubles the life of the repair.
What thread color should I use if I can't find an exact match?
A neutral color like gray, tan, or light brown is less noticeable than white on most fabrics. If the shirt is a solid color, test the thread on a hidden seam first—the inside of a cuff or the back of a collar—to see how visible it is. On patterned fabrics, match the dominant color rather than trying to match the exact pattern.
How long will the repair last?
A well-reinforced repair typically lasts as long as the rest of the shirt. The reinforcement patch or extra stitching spreads the stress across a larger area, so the seam is less likely to fail again. Wash the shirt normally; the repair will not come loose in the washer or dryer if the stitches are find.
Do I need special fabric for the reinforcement patch?
No. Any lightweight fabric works—cotton, linen, or even a scrap from an old t-shirt. Avoid thick fabrics like denim or canvas, which will create a stiff, uncomfortable lump in the armpit. The patch should be thin enough that you barely feel it when you wear the shirt.
What if the hole is right on the seam line itself?
If the hole is on the actual seam (not in the fabric next to it), you're dealing with a broken seam, not a torn hole. You'll need to remove the old stitches with a seam ripper, then re-sew the seam using a backstitch. This is more involved than patching, but the process is the same: stitch from the inside, pull the thread snug but not tight, and make the stitches small and close together for strength.