How to Sew Stretch Knit Fabric on a Sewing Machine
There's something so satisfying about sewing clothes in stretch knit fabrics. They can come together quickly, are usually easier to fit than woven garments, and of course they're super comfortable to wear!
But what if you don't have an overlocker or serger? Good news: you can sew stretch fabric on a regular sewing machine. All you need is the right needle, the right stitch, and a few simple tricks to stop the fabric stretching out as you sew.
In this guide, I will walk you through how to sew stretch knit fabrics on a domestic sewing machine, including which needle to use, the best stitches for seams and hems, and how to avoid wavy seams.
What is knit fabric?
Knit fabrics - or knitted fabrics - are made from interlocking loops of yarn, a bit like the loops in a hand-knitted jumper. This looped structure is what allows the fabric to stretch.
Woven fabrics, on the other hand, are made from threads woven over and under each other at right angles. Some woven fabrics have elastane added to them, but they don’t behave in quite the same way as knit fabrics, which are inherently stretchy.
Common stretch knit fabrics include:
- jersey
- interlock
- ponte roma
- French terry
- sweatshirt fleece
- ribbing
- stretch velvet
- activewear fabric
Because knit fabrics stretch, they’re ideal for comfy clothes such as T-shirts, sweatshirts, jersey dresses, leggings and loungewear. They also often don’t need fastenings such as zips or buttonholes, as the garment can stretch over your body.
You can find out more about handling these different types of knit fabrics in my book Stretch! Make Yourself Comfortable Sewing with Knit Fabrics.
Is sewing stretch knit fabrics hard?
Sewing stretch fabric doesn’t have to be difficult. It’s just a little different from sewing woven fabric, as they behave differently.
If you’re new to sewing knits, I'd recommend starting with a stable stretch fabric that doesn’t slip around too much. Ponte roma, double knit and sweatshirt fleece are great beginner-friendly options because they’re easier to handle than lighter weight jersey.
Save very drapey, slippery or super-stretchy fabrics for later, once you’ve got used to how knit fabrics behave under the sewing machine.
Beginner-friendly stretch fabric projects include the Drew sweatshirt, Billie sweatshirt and dress, Coco top and dress, and Nora top and cardigan add-on.
Read more about sewing with sweatshirt fleece and ponte roma.
Do you need an overlocker or serger to sew stretch knit fabrics?
No, you don’t need an overlocker - also known as a serger - to sew stretch fabric. An overlocker is a great investment for sewing stretch garments and giving seams a professional finish, but it isn’t essential.
You can sew stretch fabric on a regular sewing machine, as long as your machine has an adjustable zigzag stitch or another stretch-friendly stitch. The key is to use a stitch that can stretch with the fabric. If you sew knit fabric with a standard straight stitch, the stitches may snap when you put the garment on or move around in it.
What needle should you use for stretch knit fabric?
Use a ballpoint or stretch needle when sewing knit fabrics.
A regular sewing machine needle can cause skipped stitches, or snag the looped structure leaving little holes or pulls in the fabric.
Here’s a quick guide:
- Ballpoint needle: best for most knit fabrics, such as jersey, interlock and ponte roma.
- Stretch needle: best for very stretchy fabrics with elastane (AKA Lycra), such as activewear fabric or swimwear fabric.
- Twin ballpoint or stretch needle: useful for sewing neat-looking hems on knit garments.
For lightweight jersey, try a 60/8, 70/10 or 75/11 ballpoint or stretch needle. For thicker knits, such as sweatshirting, try an 80/12 or 90/14. If you’re getting skipped stitches, switch to a fresh needle - sometimes that’s all it takes.
What stitch should you use to sew stretch knit fabrics?
The best stitch for sewing stretch knit fabric on a regular sewing machine is usually a narrow zigzag stitch. The zigzag allows the seam to stretch without the thread snapping.
Try these settings as a starting point:
- Zigzag width: 1–1.5
- Stitch length: 2.2–2.5 for mid-weight fabrics, up to 3 for thicker fabrics like fleece
Some sewing machines also have a stretch stitch, lightning stitch or triple stretch stitch. These can work well - again, always test them on a scrap of your fabric first. Some stretch stitches are harder to unpick than a narrow zigzag, so it’s worth checking before sewing your garment.
Before you start sewing, make sure your presser foot is wide enough for the needle to make the zigzag. Turn the handwheel slowly towards you to check that the needle won’t hit the foot.
How to sew seams in stretch fabric
Use the seam allowance stated in your sewing pattern. For Tilly and the Buttons patterns, this is usually 15mm (5/8in), unless the instructions say otherwise.
Sew the seam with a narrow zigzag stitch, gently guiding the fabric through the machine.
Try not to pull the fabric from the front or back. Let the feed dogs move it through naturally. Pulling can stretch the seam out of shape and create ripples.
At the start and end of the seam, you can back tack if your machine is happy sewing backwards in zigzag. If it doesn’t like this, use a few straight stitches to secure the seam instead.
How to hem stretch knit fabric
The simplest way to hem stretch fabric is by topstitching with a zigzag stitch set to an even width and length.
Try these settings:
- Medium-weight knits: zigzag width 2.5, stitch length 2.5
- Thicker knits (e.g. fleece): zigzag width 3, stitch length 3
To help prevent rippled hems, apply an adhesive hemming tape (like Wonder Tape). I love this stuff! Stick it to the edge of the hem, peel off the backing, turn the hem up and topstitch away. And don't worry - it comes out in the first wash.
For a more ready-to-wear look, you can hem with a twin ballpoint or stretch needle. This creates two parallel rows of stitching on the right side of the garment, with a small zigzag on the underside. The zigzag underneath allows the hem to stretch.
If your machine has a three-step zigzag or multiple zigzag stitch, it’s worth testing this for hems, especially on thinner fabrics. It looks like a wide zigzag made up of tiny stitches and can help the fabric sit flatter than a regular zigzag.
Always sew a test swatch
Before sewing your garment, test your stitch settings on a swatch of two layers of your garment fabric. Check that the stitches look balanced on either side, the seam stretches without snapping, and the fabric isn’t rippling or getting chewed up by the machine.
If the stitches skip or look puckered, try changing to a fresh needle, adjusting the stitch length, or tweaking the thread tension a little at a time.
Yes, it’s an extra step - but it only takes a few seconds and can save you a lot more time unpicking dodgy stitches later.
How do you stop seams and hems stretching out when sewing stretch knit fabrics?
Rippled seams and wavy hems are one of the most common issues when sewing knit fabrics. They usually happen because the fabric has stretched while going through the machine.
Here are a few things that can help:
- Use a walking foot or dual feed foot to feed both fabric layers evenly (check if your machine already has one built in)
- Reduce the presser foot pressure if your machine allows it.
- Support the fabric so it doesn’t hang off the table.
- Avoid pulling the fabric as you sew.
- Pause with the needle down to reposition the fabric when needed.
- Press the seam after sewing to help smooth out ripples.
If your hem keeps going wavy, try wash-away adhesive stabilising tape. Stick it to the wrong side of the hem, aligning it with the raw edge, peel away the backing, then turn up the hem. The tape helps hold the layers together as they pass through the machine, and dissolves in the wash.
Shoulder seams on T-shirts and sweatshirts can also stretch out with wear. To help them keep their shape, you can stitch a strip of clear elastic, ribbon or stabilising tape into the back shoulder seam before joining to the front bodice.
Do you need to finish seams on stretch knit fabrics?
Most knit fabrics don’t fray, so you usually don’t need to finish seam allowances. Hooray!
The exception is a very loose or delicate knit, or a fabric that sheds fluff or unravels at the edges. In that case, if you don't have an overlocker, you can finish seam allowances with a zigzag stitch.
Even if you don’t finish the seam allowances, it’s still worth pressing the seams after sewing. Pressing helps set the stitches, smooth out any rippling, and make your garment look much neater.
Troubleshooting stretch fabric
Why are my stitches skipping?
Try switching to a fresh ballpoint or stretch needle. Skipped stitches are often caused by the wrong needle type, a blunt needle, or a fabric with lots of elastane.
Why are my seams popping?
Your stitch may not have enough stretch. Use a narrow zigzag stitch or your machine’s stretch stitch instead of a standard straight stitch.
Why is my hem tunnelling with a twin needle?
Tunnelling happens when the fabric rises up between the two rows of stitching. Try reducing the needle tension, using a stabiliser under the hem, or switching to a narrower twin needle.
Why does my fabric keep stretching out?
Check whether you’re pulling the fabric as you sew. Let the machine feed it through naturally, support the fabric on the table, and try a walking foot if you have one.
Ready to sew stretch knit fabrics?
Sewing stretch fabric on a regular sewing machine is absolutely doable. Start with a stable knit, use the right needle, choose a stretch-friendly stitch, and test your settings on a fabric scrap before sewing your garment.
Want a little more guidance? My Learn to Sew Jersey Tops online workshop takes you through sewing a fitted jersey top on a domestic sewing machine, step by step, with plenty of tips for cutting, stitching and finishing stretch fabric with confidence.
It's a learn-at-your-own-pace course, meaning you can watch the videos whenever you like, with no deadlines, and revisit it anytime you need a refresher.
