A combo serger-coverstitch machine does both jobs in one footprint and usually for less than two good machines, but every switch between overlocking and coverstitching costs 5 to 15 minutes of reconfiguring and rethreading. Two separate machines cost more and take twice the table space, and in return you can overlock a seam and coverstitch a hem minutes apart without touching a looper. If you sew knits every week, buy two machines; if you sew them occasionally or have one small table, a combo; if you do not own a serger yet, a serger alone plus a twin needle on your sewing machine covers most garments.
| Feature | Combo machine | Two separate machines |
|---|---|---|
| Table space | One footprint | Two footprints, about 35 × 30 cm (14 × 12 in) each |
| Cost tier | Mid-range to high-end, one purchase | Entry-level serger plus entry-level coverstitch is often comparable; two mid-range machines cost more |
| Switching between stitches | 5 to 15 minutes: needle plate, foot, knife, loopers, threads | None; both machines stay threaded |
| Threading | More complex; air threading on some models | Simpler per machine |
| Stitch quality | Equal when correctly converted | Equal; a dedicated coverstitch is less sensitive to setup |
| Coverstitch widths | 2 and 3 needles, chain stitch, often a wide top cover | Same on a mid-range coverstitch |
| Best for | Small spaces, occasional knits, one-purchase budgets | Weekly knit sewing, batch work, production |
What is a combo serger-coverstitch machine?
A serger (overlocker) sews a seam with two to four threads, trims the allowance with a knife and wraps the cut edge with its loopers. A coverstitch machine sews two or three parallel rows of straight stitching on the right side and a looper thread that covers the raw edge underneath, which is the hem you see on every store-bought T-shirt. The two machines share a lot of mechanics: loopers, differential feed, a similar bed.
A combo machine puts both in one body. In serger mode the knife cuts and the upper looper wraps the edge; in coverstitch mode the knife is disengaged, a different needle plate and foot are fitted, the upper looper is parked or converted, and the chain looper is threaded instead. Babylock, Juki (the long-standing MO-735), Janome (the 1200D) and Bernina (the L 890) have all sold combos for years, and at the time of writing (October 2026) several other brands offer one too. The coverstitch itself is identical to that of a dedicated machine once the conversion is done right.
How long does switching between serger and coverstitch take?
With practice, 5 to 10 minutes on a manual-threading combo and a little less on an air-threading one; the first few times, nearer 20 to 30 minutes with the manual open. The steps are the same on most models: raise the needles, remove or disengage the knife, swap the needle plate and foot, move the needles to the coverstitch positions, retire the upper looper, thread the chain looper and the needles, and set tensions and stitch length for the new stitch. Then the same in reverse.
Because a typical knit garment alternates (overlock the shoulders, side seams and sleeves, then coverstitch the hem and sleeve hems, then overlock the neckband and coverstitch it down), you either convert twice per garment or batch several garments so you overlock everything first and coverstitch everything at the end. Batching works well for a production run of T-shirts and badly for a single project you want to finish tonight.
What do two separate machines cost in space and money?
Each machine occupies roughly 35 × 30 cm (14 × 12 in) of table plus room for the pedal, cone stand and your hands. Two of them, next to a sewing machine, means a table at least 150 cm (60 in) long or a shelf where one lives when not in use. In a small apartment that is often the deciding factor.
On price, by tier: an entry-level serger and an entry-level coverstitch together usually land near a mid-range combo. A mid-range serger with air threading plus a mid-range coverstitch costs more than most combos, and the top combos cost as much as those two. In other words, two machines are not always more expensive; they are more expensive if you want air threading and other conveniences on both.
Does a combo coverstitch as well as a dedicated machine?
Yes, when it is set up correctly, and that is the catch. A dedicated coverstitch machine is permanently in one configuration: the loopers, plate and foot never move, so once you have found the tension that suits your jersey, it stays found. On a combo, the coverstitch depends on the conversion. A knife not fully retired, a needle plate seated slightly wrong, or a looper thread routed around the wrong guide shows up as skipped stitches or a loose looper thread, and troubleshooting means checking the conversion before checking the thread.
Combos also have a smaller free arm or none, and some have a narrower working space on the right of the needle for coverstitching a hem in the round. The best of them, with wide top cover stitches and a good manual, are superb; the cheapest are frustrating in exactly these ways.
Can you skip the coverstitch entirely?
For most home sewists, yes. A twin needle on an ordinary sewing machine gives a hem that looks like a coverstitch from the right side and stretches enough for T-shirts, sweatshirts and most dresses. Its weaknesses are tunneling on thin knits and a slightly less stretchy hem than a true coverstitch, which matters on leggings and swimwear. The twin needle vs coverstitch vs zigzag hem post compares the three.
So the decision has a step before it: do you need a coverstitch at all? If you mostly sew wovens and the occasional T-shirt, a serger alone plus a twin needle is the better purchase, and the best serger for beginners post explains what to look for. The coverstitch vs serger comparison is the place to start if you are unsure what each machine actually does.
Which should you choose?
- You sew knits weekly, or in batches of several garments. Two machines. The time you save on conversions is measured in hours over a year, and troubleshooting is easier when each machine stays in one configuration.
- You sew a few knit garments a year and want both stitches. A combo. Batch the overlocking and the coverstitching, keep the manual's conversion page nearby, and consider a model with air threading if the budget allows, because threading is the slow part of each switch.
- Your table is small and nothing else can fit. A combo, or a serger plus a twin needle. Two extra machines are hard to live with when one of them stays in a cupboard.
- You do not own a serger yet. Start with a 4-thread serger and a twin needle. Add a coverstitch later if you find twin-needle hems limiting; by then you will know whether a combo or a dedicated machine suits the way you work.
- You sew activewear, swimwear or sell what you make. Two machines, and a dedicated coverstitch with a wide top cover. Those hems get stretched hard and often, and the chain stitch on a well-set dedicated machine is the most reliable.
A pattern designed for knits helps either way: Sewly's T-shirt and sweatshirt patterns use a 1 cm (3/8 in) seam allowance by default, which matches a serger's standard cutting width, so there is nothing to trim before the knife.