What a Blind Hem Does and Why Your Machine Can Do It

A blind hem is a stitch that hides almost completely on the outside of the fabric—the thread runs inside the fold of the hem so only tiny dots of thread show. On a sewing machine, you create this effect using a special presser foot and a zigzag stitch that catches just a thread or two of the outer fabric, then travels inside the fold. The result looks nearly invisible from the front, which is why tailors use it on dress pants, skirts, and formal wear.

Most modern sewing machines have a blind hem stitch built in—usually stitch number 10 through 20, depending on your model. Check your manual for the exact number and the recommended presser foot. Some machines call it a "blind stitch," others a "blind hem stitch." If your machine does not have this stitch, you can still hand-sew a blind hem, but the machine version is faster and more even for beginners.

Key Takeaways

  • You need a blind hem presser foot (sometimes called a blind stitch foot), which has a guide that keeps the fold of fabric centered under the needle.
  • Fold and press your hem to the finished length before you sew—the machine stitches into an already-folded edge, not a raw one.
  • Thread color matters: use thread that matches the pant fabric, not the hem fabric, because the visible stitches will be on the outside of the pant leg.
  • Test your stitch on a scrap of the same fabric folded the same way, because the needle position and stitch width need adjustment for your specific material.
  • The most common mistake is sewing too close to the fold, which makes the stitch visible on the outside—the needle should catch only a single thread of the outer fabric.

Prepare Your Hem Before You Sew

Start by trying on the pants and marking the finished hem length with a pin or chalk. Stand in the shoes you will wear with the pants, and have someone mark where the hem should hit—usually at the top of your shoe or just touching the floor. Mark both legs at the same height.

Cut the hem allowance to 1.5 inches below your marked line. Fold the raw edge up 0.5 inches and press it with an iron to create a crisp fold. Then fold the entire hem up to your marked line and press again. You should now have a folded hem that is 1 inch deep, with the raw edge hidden inside. Let the hem cool completely before you move to the machine—a warm hem will shift as you sew.

Pin the folded hem in place, spacing pins about 4 inches apart around the entire pant leg. Pin from the inside so the pins do not get in the way of the presser foot. Try on the pants one more time to confirm the length is correct before you sew anything permanent.

Set Up Your Machine and Presser Foot

Install the blind hem presser foot according to your machine's manual. This foot has a metal guide on the left side that holds the fold of the hem centered under the needle. The needle will zigzag slightly—it travels to the right to catch a thread of the outer fabric, then back to the left to travel inside the fold.

Select the blind hem stitch on your machine. Set the stitch width to 2.0 to 2.5 mm and the stitch length to 2.0 to 2.5 mm. These are starting points; you will adjust them after testing. Use thread that matches the color of the pant fabric (the outer leg), not the hem fabric. Wind a bobbin with the same thread. If you are hemming dark pants, use dark thread on top and in the bobbin.

Set the machine to a medium presser foot pressure. If your machine has a dial, aim for the middle setting. Too much pressure will pucker the fabric; too little will cause skipped stitches. Check your manual for the recommended needle type—most blind hem work uses a universal needle in size 80/12 or 90/14, depending on fabric weight.

Test Your Stitch on Scrap Fabric

Cut a piece of the same pant fabric about 6 inches square. Fold it the same way you folded your hem: fold the raw edge up 0.5 inches, press, then fold the entire piece up 1 inch and press. This scrap should feel and look exactly like the hem you will sew on the actual pants.

Place the scrap under the presser foot with the fold on the left side, aligned with the metal guide on the foot. The guide should sit just inside the fold, not on top of it. Lower the presser foot and take three or four stitches. Stop and lift the presser foot. Examine the stitches on the outside of the fabric—you should see only tiny dots of thread, spaced evenly, with no visible line of stitching.

If the stitches are too visible, the needle is catching too much fabric. Reduce the stitch width by 0.5 mm and test again. If you see skipped stitches or loose loops, increase the presser foot pressure slightly or reduce the stitch length by 0.5 mm. Keep testing until the outside looks nearly invisible. Write down your final settings so you remember them for future projects.

Sew the Hem on Your Pants

Place the first pant leg under the presser foot with the folded hem facing you and the fold aligned with the metal guide. The guide should sit just inside the fold—if it sits on top of the fold, the needle will miss the outer fabric. Lower the presser foot and sew slowly, guiding the fold along the guide with your fingers. Do not pull the fabric; let the machine feed it.

Sew all the way around the pant leg, removing pins as you approach them. When you reach the starting point, overlap your stitches by about 0.5 inches, then backstitch to lock the thread. Raise the presser foot and remove the pant leg. Trim the thread tails close to the fabric.

Repeat the same process on the second pant leg, using the same settings. Try on the pants to check the hem length and the appearance of the stitching. From the outside, you should see almost no thread. From the inside, you will see a line of zigzag stitches running along the fold.

Finish and Press Your Hem

Once both legs are sewn, press the hem from the inside with a warm iron. Use a pressing cloth (a thin cotton cloth or even a clean tea towel) between the iron and the fabric to avoid shine marks. Press gently—do not drag the iron, which can stretch the hem. Let the hem cool before you try on the pants.

Check the outside of the hem one more time. If you see a line of stitching, it means the needle was catching too much fabric. You can carefully trim away the excess hem allowance from the inside (the part that was folded up) to reduce bulk, but do not cut into the stitches themselves. A small amount of visible thread is normal and will fade with wear and washing.

Common Mistakes and How to Avoid Them

The most common error is sewing too close to the fold, which makes the stitch line visible on the outside. The metal guide on the blind hem foot is there to prevent this—keep the fold aligned with the guide, not pushed against the needle. If the guide is not centered on your foot, check that the foot is installed correctly.

Another frequent problem is puckering or gathering along the hem. This usually means the presser foot pressure is too high or the fabric is being pulled as it feeds. Reduce the pressure and let the machine do the work. If puckering still happens, check that your needle is not bent or dull—a damaged needle will cause tension problems.

Skipped stitches often mean the needle is too small for the fabric weight or the presser foot pressure is too low. Try a larger needle (size 90/14 instead of 80/12) and increase the pressure slightly. If you are hemming heavy fabric like denim or canvas, use a needle made for heavy fabrics.

Frequently Asked Questions

Can I use a blind hem stitch on knit fabrics like jersey or sweatpants?

Yes, but knits need a stretch needle and a lighter touch. Use a ballpoint or stretch needle in size 75/11 or 80/12, and reduce the stitch width to 1.5 mm. Test on a scrap first, because knits can curl and shift as you sew. Some sewers prefer a narrow zigzag stitch on knits instead of a true blind hem, because it allows the fabric to stretch without breaking the thread.

What if my machine does not have a blind hem stitch?

You can sew a blind hem by hand using a needle and thread, which takes about 20 to 30 minutes per pant leg. Alternatively, use a narrow zigzag stitch (width 1.5 mm, length 2.0 mm) with matching thread, sewing close to the fold from the inside. It will not be completely invisible, but it will be much less noticeable than a straight stitch.

How do I fix a blind hem that came loose after washing?

Check the thread tension and needle condition first—a loose hem often means the bobbin tension was too loose or the needle was dull. Re-sew the loose section using the same stitch settings, overlapping the old stitches by about 1 inch on each side. If the entire hem failed, you may need to remove all the old stitches and start over.

Should I use the same thread color in the bobbin as on top?

Yes. The bobbin thread will show on the inside of the hem, and if it does not match the top thread, the stitches will look uneven. Use the same color thread in both the top and bobbin for a professional finish.

Can I blind hem pants that are already hemmed with a straight stitch?

You can, but you will need to remove the old stitches first. Use a seam ripper to carefully cut and pull out the old thread, then press the hem flat with an iron. Fold and press the hem again as if it were new, then sew the blind hem stitch over the same fold line. This works best if the original hem was sewn close to the fold—if it was sewn far from the fold, you may not have enough fabric to work with.