What is an Overlock Stitch?

December 9, 2020

An overlock stitch is used to create seams, hems, and edges on fabric to complete a sewing project. It is somewhere between a zigzag and a straight stitch. It is also used to attach pockets to jeans. An overlock stitch is very similar in appearance to serging. It will finish your sewing projects off beautifully and lend them a very professional appearance. It is used to join seams, prevent hems from fraying, and can even cut off any excess fabric. This last one is only applicable to sewing machines with inbuilt cutters. On all others, you will need to cut off any excess fabric by hand.

What is an Overlock Stitch
close up image of a sewing machine

How do you do an overlock stitch?

Overlock stitches are created by sewing 3 parallel lines of straight stitches. Between each pair of lines, a zigzag is sewn.To create an overlock stitch, you will need an overlocker or serger. All this means is that your machine can sew anywhere between 3 and 5 threads at the same time. These machines usually operate at a speed of between 1,000 and 9,000 revolutions per minute.

What is the difference between a sewing machine and an overlocker?

An overlocker is a specific type of sewing machine. It is created to sew together the edges of multiple fabrics using an overlock or overcast stitch.

Most overlockers will also have an inbuilt cutter to trim any excess seam allowance. Some sewing machines have this function built in to hem and edge your sewing projects. Overlockers can use between 3 and 5 thread types at once to create a stitch. Ordinary sewing machines tend to only utilize 2 threads at once.Overlockers have telescopic needle bars to allow the different thread types to pass through once they have left the thread cones. It sits horizontally above the neck of an overlocker and is not found in traditional sewing machines. With a sewing machine, you have the capacity to sew on the left or right-hand side of the needle. Overlockers will only allow you to serge on the left of the needle.

What are the types of overlock stitches?


Single overlock stitches use one thread to create the stitch.

This type of stitch is best suited to butt seaming for textiles and end-to-end seaming.


This is a very common type of overlock stitch, using 2 threads to create it. It is very multifunctional and can be used for a variety of purposes.

These include adding lace or elastic to lingerie, general hemming, finishing the edges of seams, seaming and edging woven fabrics, and stitching flat-lock seams.


This is generally used more for decorative purposes. It is very well-suited to knitted and woven fabrics.

It is useful for finishing edges of garments too. This stitch can also be used to sew pin tucks and create narrow rolled hems.


This is a very strong stitch and tends to be used to reinforce areas of garments that are under high tension and pressure.

It is not only strong but flexible too. This means that it is perfect for decorative edging and finishing off garments.


This is even stronger than a 4-thread stitch and is perfect for using on heavier weight fabrics such as hessian, denim, and terrycloth.

This feature is usually only found in more expensive overlocking devices. It is a combination of a 2-thread chain stitch and a 3-thread overlock stitch.

What are the benefits of an overlocking machine?

Uses loopers

The machine uses loopers in the machine that are located under the needle. They act like knitting needles to add thread to your needle. These act as bobbins, but have the added benefit of being able to use more than one thread at a time. The loopers will feed multiple thread cones into the needle mechanism. It incorporates loose edges into the seam and gives your garment a more polished finish.

It’s fast

Most overlockers can sew about 1,600 stitches per minute.

Standard sewing machines can only manage around half of this. This makes it much more easy and rapid to finish off your projects.

Makes your projects appear more high-quality

An overlocking stitch, when done correctly, creates a very high-quality looking finish. It should appear similar to the stitching used to make professional clothing garments. Most overlockers will also have an inbuilt cutter to cleanly snip away any excess fabric.

Increased strength and flexibility

Overlockers create hems and edges that are stronger and more flexible than a sewing machine can.

This is due to the multiple threads incorporated into the stitching.


There are no standard sewing machines that can do all of the functions of an overlocker.

These machines are capable of overcasting, sewing, and cutting simultaneously.

How do you hand sew an overlock stitch?

You will need:

  • Thread, the same color as the fabric
  • Needle
  • Pins
  • Scissors


Your first step is to thread the needle - be sure to use a thicker needle for thicker fabrics. Tie off the ends with a knot. Place two pieces of fabric with the right sides facing one another. Ensure they are perfectly lined up and pin them in place. Make sure the pins run perpendicular to the seam direction. You will first need to thread your needle through one piece of fabric but not the other, beginning from the right side of the fabric. This will allow your knot to hide. Leave a 3-4mm seam allowance. Sew back along the stitching and join the two pieces until you return to the first hole. Loop the thread around the seam allowance to create your first overlock stitch. Pull the two layers together, ensuring the fabric is not wrinkled or ruched. Go around the edge of the fabrics again and stitch together to return to the right side. This is your second overlock stitch and should be spaced about 3-4mm apart. Continue in this way along the seam and finish with a half stitch, and cut off any excess thread.

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