What Does an Overlocker Sewing Machine Do?

An overlocker is a specialized type of sewing machine that produces overlock stitches to sew over one or two pieces of cloth. In most cases, overlockers are used for edging, hemming, or seaming. Additionally, overlocker sewing machines that come with built-in blades will also trim off excess fabric along the edges to prevent fraying. Such machines are commonly known as “sergers” in North America.

Most sewing machines can create a lockstitch to enclose the seam allowance or finish the edges of fabric. However, an overlocker uses loopers to feed multiple thread cones rather than a bobbin, which is the case with conventional sewing machines that have lockstitch capability.

Types of Overlock Stitches and their Applications

Overlock stitches can use anywhere between 2 and 5 spools of thread simultaneously. As such, the easiest way to categorize these stitch patterns is by the number of threads used. Each of these thread formations have unique benefits and uses as described below:

  • Single/1-Thread Overlock Stitch
    This stitch is mostly used for butt-seaming or end-to-end seaming of piece goods for textile finishing.
  • Double/2-Thread Overlock Stitch
    Common in almost every overlock sewing machines, the 2-thread overlock stitch has many uses. It helps with edging and seaming woven fabrics, attaching elastic and lace to lingerie, stitching flatlock seams, finishing seam edges, or general hemming.
  • Triple/3-Thread Overlock Stitch
    The triple thread overlock stitch is a popular choice for decorative edging. Like the 2-thread overlock stitch, this stitch pattern also helps to seam knit or woven garments as well as finish fabric edges. The 3-thread overlock pattern is also an excellent stitch for sewing pintucks and creating narrow rolled hems.
  • 4-Thread Overlock Stitch
    If you want to seam high-stress areas, the 4-thread overlock pattern is the best choice. This overlock mimics a safety stitch in strength while retaining flexibility. It’s also good for decorative edging and finishing.
  • 5-Thread Overlock/Safety Stitch
    More expensive overlockers have the capability to sew a 5-thread safety stitch. The safety stitch is a combination of a 2-thread chainstitch and a 3-thread overlock. It creates a strong seam for heavy weight fabrics such as denim and terrycloth. Overlockers that offer a 5-thread safety stitch eliminate the need to reinforce the seam with an additional straight stitch from a conventional sewing machine.

Most, if not all, overlockers provide the option to vary stitch width and density. You can also add variation in stitch types if your machine has an adjustable differential feed function. For instance, using an extra fast feed creates a “lettuce-leaf” or wave-like effect on fabric edges.

Other Uses for an Overlocker Sewing Machine

An overlocker sewing machine does not just sew two layers of clothing with an overlock stitch, trim the edge of fabric to stop fraying, and give that professional finish to your sewing projects. It can also perform a variety of other functions.

For instance, upper end units have the ability to create a coverstitch. This double-needled top stitch is mostly sewn on cuffs to cover raw seams and edges. No doubt, it’s possible to create a coverstitch using an ordinary double-need sewing machine. However, the seam will not have the same stretch capability that an overlocker/serger creates.

Speaking of stretching capabilities, overlockers create a stitch pattern that allows for an incredible amount of stretch. Consequently, overlock stitches are very useful for attaching elastic or sewing knitted fabrics.

Depending on the make and model, overlocker machines can help to create flatlock stitches, decorative edging, rolled hems, and other trims or embellishments. Other overlockers even assist with adding beads, sequins, laces or cording.

Should You Buy an Overlocker?

Whether to buy an overlocker or not comes down to your particular sewing needs. If you only sew on occasion when the need to mend clothing arises, then such a machine would probably not be worth it as there are several cheaper alternatives. For instance, some conventional sewing machines work with a cut and hem overlock attachment. Alternatively, other stitches such as the zigzag or lockstitch can prevent fabric from fraying if sewn close to the edge.

However, if you do a lot of sewing, an overlocker would come in handy. Here are some of the pros and cons to expect from this type of sewing machine:


  • Overlockers create an overlock stitch on edges and trim excess seam allowance all in one-step. These machines are fast as well. Most units sew up to 1600 stitches per minute, which is almost twice the speed of ordinary sewing machines. As a result, an overlocker is a real time saver.
  • Overlockers provide a professional finish to your sewing projects.
  • These machines are excellent for attaching elastic.
  • Overlockers provide versatile functionality. A unit will offer functions for many other sewing tasks such as decorative edging and rolled hemming.


  • Learning to thread an overlocker can be a bit tricky. However, it does get easier with time and practice.
  • Overlockers are not stand-alone sewing machines that can “do-it-all”. You will still need to use a regular sewing machine for topstitching or inserting buttonholes and zippers.
  • In addition to owning a conventional sewing machine, buying an overlocker can seem to be an extra expense.

In conclusion, it is important to note that an overlocker should be used alongside an ordinary sewing machine and not in place of one. The reason for this is that overlockers are somewhat limited in capability when compared to conventional sewing machines.

While having two separate sewing units can seem costly, owning an overlocker sewing machine pays off if you’re a professional tailor or work on garment construction projects that require a professional finish.

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