How to Choose a Serger: Thread Count, Differential Feed and Air Threading

Serger vs sewing machine: do you need a serger?

You need a serger if you sew knit garments often, or if you want woven seam allowances finished neatly without zigzagging every edge. You can live without one if you mostly quilt, make home decor, or sew a few garments a year, because a zigzag or overcast stitch on a regular machine finishes edges well enough.

Here is the practical difference. A serger stitches, trims and overcasts at up to 1,300 or 1,500 stitches per minute, and its looped stitches stretch with knit fabric. A sewing machine is slower at seam finishing but does everything else. Most garment sewists end up with both side by side. Our serger vs sewing machine comparison explains which jobs belong to each.

3 thread vs 4 thread serger: what is the difference?

A serger uses one or two needles on top and two loopers underneath. Loopers are curved hooks that carry thread around the fabric edge. The number of threads describes how many of those are in use for a stitch.

For most home sewing, 3 and 4 thread stitches are all you need. The 2-thread option is a genuine bonus for sheer fabrics and fine rolled edges, and it is one reason sewists step up from a Brother 1034D to a Juki MO-654DE. A 5-thread machine matters mainly if you sew many heavy woven garments.

What is differential feed on a serger, and why does it matter?

Differential feed means the serger has two sets of feed dogs, front and back, that can move at different speeds. It is the single most important serger feature for knits.

• Setting above 1.0 pushes extra fabric under the foot, so stretchy knits do not wave or ripple along the seam.
• Setting below 1.0 holds lightweight fabric taut, so it does not pucker.
• Turned well up, it gathers light fabric on purpose for ruffles.

Every serger in this guide lists it, but the range differs. The Janome 8002D, Janome MyLock 634D and Elna eXtend Covermax list a ratio of 0.5 to 2.25. The Singer S0100 lists adjustable differential feed without a published ratio. When comparing models, a wider range gives more control on very stretchy or very fine fabric.

Is an air threading serger worth it?

Threading is the part of serging people dread. On a conventional serger you follow a color-coded path through small guides for each looper, often with tweezers, in the order the manual specifies. On an air threading serger, you place the looper thread in a port, press a lever or button, and air blows it through a tube and out the looper eye.

It is worth it in three situations: your hands or eyes make small guides difficult, you change thread colors often, or a previous serger sat unused because threading was stressful. It is not worth it if you sew mostly with neutral serger thread and rarely rethread, since the tie-on method (knotting new thread to old and pulling it through) handles most color changes. Air threading does not make better seams; it makes getting threaded correctly easier.

Note that air threading covers the loopers only. Needles are still threaded separately, which is why the built-in needle threader on the Janome AirThread 2000D is worth noticing. The full breakdown is in air threading vs regular serger.

Serger vs coverstitch: which do you need, or should you buy a combo?

A coverstitch machine sews hems, not seams. It uses two or three needles and one looper, with no knife, to make parallel straight lines on top and a stretchy looper chain underneath, like the hem on a T-shirt. For almost every garment sewist, the serger comes first, because every garment needs seams and not every garment needs a coverstitched hem. A twin needle on a regular sewing machine covers occasional knit hems.

Combos make sense for small rooms and sewists who work in batches. If you switch between seaming and hemming within a single garment, two machines side by side are faster. See serger vs coverstitch and the best coverstitch machines.

How much should you spend on a serger?

• About $250 to $360. The Singer S0100, Brother 1034D, Brother ST4031HD and Janome 8002D all sew 3 and 4 thread seams at 1,300 stitches per minute. The Singer S0100 also lists 2-thread options, and the Brother ST4031HD adds an extension table. This tier suits most people buying a first serger.
• About $600 to $700. The Juki MO-654DE and Janome MyLock 634D add 2-thread stitches and, on the Janome, a listed cutting width of 3.1 to 7.3 mm. The Singer 14T968DC adds 5-thread stitches and automatic self-adjusting tension. This tier suits weekly garment sewists.
• About $900 to $1,400. Air threading on the Brother AIR1800, Brother Airflow 3000 and Janome AirThread 2000D. This tier is about comfort and time, and it is the right spend for anyone whose hands or eyes make threading a chore.

Who should not buy the top tier: sewists who rarely change thread colors and are comfortable with manual threading. The seams will not be better, and the savings would buy a coverstitch machine. Our best sergers for beginners ranks starter picks, and best sergers covers the whole range.

Do you need special thread and needles for a serger?

Use serger thread on cones. Sergers use a lot of thread, often 3 or 4 cones at once, and cones such as the Maxi-Lock 4 Cone Pack (4 cones of 3,000 yd spun polyester) cost far less per yard than small spools. Neutral colors blend on the inside of most garments, so many sewists keep white, black, grey and beige loaded.

For needles, follow the manual exactly. Many home sergers, including the Juki MO-654DE, take household HAx1 needles, the same system as the 130/705 H needles in most home sewing machines. Some sergers and coverstitch machines specify ELx705 needles, such as the Schmetz ELx705 Needles. The sewing machine needle size chart explains sizes, and our how to use a serger guide walks through your first seams.