How to Fix a Belt Loop on Jeans

Assess the Damage

Before sewing, you need to know exactly what you're working with so you know the materials required for the repair. With a particularly bad tear, the fabric under the belt loop is usually shredded as the loop rips from the jeans. Even if the loop tears off completely, there's no need to throw away an otherwise perfect pair of jeans––the mending job can still be done easily and even creatively.

Examine the size of the hole left where the belt loop came off; you'll need a scrap of fabric slightly bigger than that to patch it. Keep any threads of the denim that remain in the hole. Use your finger or the tip of an iron to press them into the hole to fill it in as much as possible.

Patch the Hole

If a hole was created where the belt loop ripped off from the jeans, then you will need to fix it before you sew the loop back on. To repair the hole, follow these steps:

1. Trim the scrap of fabric so it's about 1/4" larger all around than the hole. Place the patch of fabric on the inside of the jeans under the hole. Temporary spray adhesive will keep the threads and scrap stay in place. ​Fusible tape or webs can also be used, but they may add extra bulk and still need to be secured by stitching to be strong enough to hold a belt loop. 
2. If you have one, insert a Microtex or denim sewing machine needle in a size 90/14 in the sewing machine. A sharp, sturdy needle will make sewing through the many thick layers easier.
3. Thread the sewing machine with the thread that matches the denim color in both the upper thread and bobbin.
4. Adjust the stitch length and width to sew a wide and elongated zigzag stitch.
5. Place the jeans, right side out, on the bed of the sewing machine.
6. Making sure that the loose threads of the hole and the fabric scrap are flat and in place, zigzag stitch around the edge of the hole to hold the threads and patch in place. The amount of zigzag stitching will depend on the size of the hole, but you will zigzag just enough to "tack" the patch and threads in place, not to close the hole.
7. Set the sewing machine to a straight stitch.
8. Sew back and forth over the hole, horizontally and then vertically, to completely close the hole as if your stitching is new fabric, with no gaps in the stitching.

Sew on the Belt Loop

Once the hole is repaired where the belt loop attaches to the jeans, you are ready to sew the belt loop back on:

1. Thread the sewing machine with matching topstitching thread (keep the bobbin thread the same as before).
2. Refer to your sewing machine manual to set the stitch width and length for a bar tack or set it for a short, narrow zigzag stitch. (You may want to test it first on a folded scrap.)
3. Remove any loose thread that remains from the original stitching that held the belt loop in place.
4. Line up the belt loop with its original position. Sew, placing the stitching where the original stitching was on the belt loop, sewing back and forth until the loop is sewn tightly to the patched fabric under the belt loop.
5. Trim all of the threads, and your jeans are ready to wear.