How to Mend: How to Hem Knit Pants with a Double Stretch Stitch (Twin needle / Double needle)

Are your knit stretchy pants dragging on the floor?  Learn how to use the stretch stitch and a twin needle to sew a new hem on those knit pants!

The stretch stitch is built into some sewing machines and is used to sew knit or other stretchy fabrics.  This stitch goes back and forth to make a stitch that can stretch with the fabric.

Using the twin needle, the hem of the pants can be stitched quickly with two parallel seams.

So, get those pants ready and follow our video and photo tutorial to sew a new hem on those pants!

If you are looking to hem dress pants, follow the link to our tutorial on How to Fix a Hem on Dress Pants.

WHAT YOU NEED:

• Knit Pants Needing a Hem
• Twin Needle
• Two spools of matching thread & matching bobbin
• Sewing Machine with a Stretch Stitch setting

How to hem stretch fabric

The photo below shows the original hem from the knit pants. It was cut off and I tested serging the edge to adjust the differential feed.  So, that is why there is overlock stitching along the cut side.

The original seam had a double line of stitches, made with a cover stitch machine.  This is a specialty machine that most home sewists will not have, so I had to use an alternate method to replicate the seam for the hem of the pants.  The twin needle is a perfect choice that will replicate the two rows of stitching.

The photo below shows the first pant leg finished with the double stretch stitch and the twin needle.

STEP 1: Setup machine with twin Needle 

First, set up the sewing machine with the twin needle.  This type of needle will work in most sewing machines.  A sample twin needle is shown below in the photo.

What is a Twin Needle?

A twin needle (see photo above) is a quick way to stitch a double seam with two rows of parallel stitches.  The twin needle is a specialty needle with two needles attached to a single shank, so it can be used with any sewing machine.  As the needle stitches two parallel rows simultaneously, the bobbin thread will zig-zag between the two rows of stitches.

Twin needles come in different widths and this one is 4mm between the two needles.  Place the twin needle in the sewing machine like any other needle.  Be sure to use your standard presser foot.

Threading the machine with a twin needle is a bit different than threading with one thread only. Click the link to see a more detailed tutorial on threading a twin needle.

Thread your first thread as you normally do and use both the needle bar thread guide and thread the needle on the left side.

Most sewing machines will have an extra spool pin.  Use this spool pin for the second spool of thread.

Thread the second thread through the machine as you normally do but at the needle bar thread guide and needle, thread using the right side.

Thread your bobbin with a matching thread.  The bobbin will be on the back side of the hem and will not be seen.

Step 2: Prepare the Hem

Prepare to hem the pants by removing the old hem and trimming off the extra fabric.  Serge or zig-zag the cut edge of the fabric to finish it and keep it from fraying in the future.

Fold up the new hem, iron, and pin it in place.

Step 2: Stitch the stretch Stitch

Set the sewing machine on the stretch stitch.  On my Bernina Activa 240, the stretch stitch is the #6 stitch.  This stitch symbol is three dotted lines and three zig-zag lines.

What if my machine doesn't have the stretch stitch?

For machines without the stretch stitch, I would recommend using a narrow zig-zag set to the standard length stitch to create the hem. If a matching thread is used, it shouldn't be very noticeable. The zig-zag stitch will have some give and be able to stretch similarly to the stretch stitch.

What is the stretch stitch?

The stretch stitch is an ideal stitch for sewing stretchy knit fabrics.  The pattern of the stitches makes the fabric able to be stretched without breaking the thread.  When the machine is stitching the stretch stitch, it will move in a forward, back and forward pattern for each stitch.  This pattern of stitching allows the thread to stretch with the fabric.

Remove the work table from your machine.  For hemming pants, it's easiest to put the pant leg around the arm of the sewing machine.  Place the leg under the presser foot.

The right side of the fabric must be facing up for this stitch.  The bobbin thread will wrap around both top threads while stitching and the double line of stitches will only appear on the top side.

Start stitching the seam by following the seam guide for the size seam being sewn.  Back tack at the beginning and end.

As you stitch, the machine will move forward a few stitches, then backward and forward again.  Allow the fabric to move back and forth as the machine stitches.  Two lines of stitches will be sewn.

Complete! Double Stretch Stitch Hem is Finished

Below is a photo of the finished double stretch stitch hem from the right side.  There are two lines of stitches.  If the fabric is stretched a bit, the stitches will give with the stretch.

Below is a photo of the back (inside) of the double stretch stitch.  See how the bobbin has wrapped across and between the two rows of stitches.

More Mending Tutorials:

• How to Fix a Hem on Dress Pants
• How to Shorten Dress Pants with Hem Tape
• Learn How to Fix a Stained Shirt by Tie-Dying It
• How to Patch Small Holes in Pants
• How to Patch Holes in Pant Legs
• How to Mend a Ripped Bed Sheet
• How to convert a flat sheet to a fitted sheet