Overlocker vs coverstitch machine

How the two stitches differ

An overlock stitch is formed on the edge of the fabric. On a 4 thread overlock, two needle threads sew parallel seam lines while the upper and lower looper threads wrap around the raw edge. The knife trims the seam allowance just before the needles, so you get a sewn, trimmed and enclosed seam in one pass.

A coverstitch is formed away from the edge, on the flat of the fabric. Two or three needles sew parallel lines on the right side, and a single looper underneath carries a thread that zigzags between them on the wrong side. There is no knife. The looper thread can cover a raw hem edge on the inside, which is how ready to wear T shirts are hemmed.

The diagram shows the two stitches on a knit hem, with each thread labelled, so you can see why one sits on an edge and the other on the face of the fabric.

What each machine is best at

Choose by the job rather than the machine. If most of your time goes on constructing knit garments, the overlocker does the heavy lifting. If your seams are fine but your hems look homemade or pop when stretched, the coverstitch is the missing piece.

Three machines compared from their listings

The Janome 8004D is a 3 and 4 thread overlocker, the Janome CoverPro 2000CPX is a dedicated cover hem machine, and the Juki MO735 is a combination machine that offers a 5 thread safety stitch alongside coverstitch and chain stitch. The table uses only listing details and marks gaps as not stated.

Compare coverstitch and combination machines →

When a combination machine makes sense

A combination machine such as the Juki MO735 overlocks and coverstitches in one body, which saves table space and buys one machine instead of two. The trade off is changeover. Moving from overlocking to coverstitch on most combination machines means rethreading, moving or covering the knife and changing settings, so you cannot sew a seam and then hem straight away without converting it.

That suits someone who batches work: overlock every seam on a garment, convert once, then hem everything. If you prefer to finish one piece at a time or sew a lot of knitwear, two dedicated machines side by side are quicker to work with. Check the manual for the exact changeover steps, as they vary between makers and models.

Note:Switch off and unplug before changing needles, swapping between overlock and coverstitch set ups or opening the looper cover. For motor, wiring or timing faults, use a qualified sewing machine engineer.

Which to buy first

For most home sewists, the overlocker comes first. It speeds up every knit seam and neatens woven seams too, so it earns its place on more projects. A coverstitch is a specialist second machine for people who sew a lot of T shirts, leggings, activewear or swimwear and want hems that look and stretch like ready to wear.

Before you buy either, remember a standard sewing machine can hem knits with a twin needle and a stretch thread in the bobbin. The result stretches less and can tunnel on light jersey, but it is a reasonable stop gap. If you have not bought an overlocker yet, our guide to overlocker vs sewing machine and the best overlockers for beginners are good next reads.

1. 1

   List the last five garments you made and note whether the slow part was seams or hems.

2. 2

   If seams and edge finishing slowed you down, start with an overlocker.

3. 3

   If seams were fine but hems let you down, consider a coverstitch.

4. 4

   If you want both and have limited space, look at a combination machine and accept the changeover time.

Threads, needles and set up

Both machine types run from cones and use more thread than a sewing machine. A coverstitch uses fewer threads at once than a 4 thread overlocker, but you will still want matching cones for visible hems. Woolly nylon in the looper gives a softer, stretchier finish on swimwear and activewear on many machines.

Needle systems differ between brands and between overlockers and coverstitch machines, so check the manual before buying spares. Differential feed matters on both: our differential feed explainer covers how to stop waves and puckers, and the same principle applies to coverstitch hems.

Frequently asked questions

Can an overlocker do a coverstitch? A standard 3 or 4 thread overlocker cannot. You need a dedicated coverstitch machine or a combination machine that lists coverstitch among its stitches, such as the Juki MO735.

Can a coverstitch machine sew seams? It can topstitch and sew flat decorative seams, but it does not trim or wrap the edge, so it is not a substitute for an overlocker on knit seams.

Is a coverstitch the same as a twin needle hem on a sewing machine? They look similar from the right side. The difference is underneath: a coverstitch has a looper thread zigzagging between the needle lines, which stretches more and can enclose the raw edge, while a twin needle relies on a single bobbin thread.

Is a combination machine harder to use? It asks for more set up, because converting between modes means rethreading and changing parts. Once set, each mode works much like a dedicated machine. Follow the manual carefully during changeover.