How to Sew with Knit Fabric: Techniques for T-Shirts, Jersey, and Stretch Fabric

Knit fabric is the material of T-shirts, leggings, sweatshirts, and most modern casual wear. It stretches, recovers, and shapes around the body — the very thing that makes it comfortable to wear is what makes beginners afraid of sewing it. The fabric stretches under the presser foot. It curls at cut edges. It skips stitches if you use the wrong needle.

But with three small adjustments — the right needle, the right stitch, the right technique — knits are no harder than wovens. Many home sewers find them faster and more forgiving once the techniques are familiar.

This guide covers how to sew knit fabric cleanly on a regular sewing machine. A serger helps but isn’t required.

Knit vs woven — the structural difference

A quick refresher (covered in detail in our complete fabric types guide):

Wovens have yarns crossed at right angles in a stable grid. They don’t stretch much. Cotton poplin, denim, linen.
Knits have looped yarns that interlock. They stretch — usually more in the widthwise (crosswise) direction than lengthwise.

This stretch is what makes knits comfortable but also what creates the sewing challenges:

The fabric stretches as it feeds through the machine if not handled carefully.
A regular straight stitch breaks when the fabric stretches (the thread snaps).
Cut edges curl, making cutting and assembly trickier.

The three essential adjustments

Before sewing knits, change three things on your machine:

1. Use a ballpoint or stretch needle

Universal needles (the default) have slightly sharp points that can split or pull individual yarn loops in knit fabric, leaving small holes or runs. A ballpoint needle has a rounded point that pushes between the loops without piercing them. A stretch needle is similar with a slightly different scarf design optimized for very stretchy synthetic fabrics.

For most knits — jersey, ponte, French terry, sweatshirt fleece — use a ballpoint 80/12. For very stretchy fabric (spandex, swimwear, scuba), use a stretch 75/11.

For more on needle choice by fabric, see our needle and thread guide.

2. Use a stretch stitch, not a straight stitch

A straight stitch on knit fabric breaks when the fabric stretches. The thread isn’t elastic and the stitches snap. Use one of these instead:

Zigzag stitch (narrow): a shallow zigzag (1.5 mm wide × 2.5 mm long) that has enough give to stretch with the fabric.
Stretch straight stitch (or triple straight): a stitch that sews forward, back, forward — looking like a straight line but constructed with three threads at each point. Stretches with the fabric.
Lightning bolt stitch: a special stretch stitch on some machines, looking like a lightning bolt shape.
Twin needle stitch: parallel rows of straight stitching from a twin needle, with the bobbin thread zigzagging between them underneath. Used for hems.

Test on scrap. Stretch the seam after sewing — does the thread break? If yes, the stitch isn’t stretchy enough.

3. Use a walking foot if available

A regular presser foot can stretch the top layer of knit fabric as it’s pushed by the foot, while the bottom layer is fed cleanly by the feed dogs. The result: one side of the seam is longer than the other, and the seam ripples.

A walking foot has its own feed dogs that sync with the machine’s, feeding both layers evenly. It’s not strictly required for knits, but for any garment with long seams it dramatically improves results. Our walking foot guide covers when and how to use one.

If you don’t have a walking foot, you can still sew knits — just sew slowly and don’t pull the fabric. Let the machine feed it.

Cutting knit fabric

Knit fabric is more challenging to cut than wovens because it stretches under shears.

Tips:

Use a rotary cutter and mat

A rotary cutter with a sharp blade gives much cleaner cuts on knits than shears. The fabric doesn’t lift or stretch.

Don’t pin too tightly

Pins distort knit fabric. Use as few as possible, place them in seam allowances rather than the body of the piece, or use pattern weights instead.

Pre-treat first

Knits shrink. Wash and dry your fabric the way you’ll wash the finished garment before cutting. See our pre-treating fabric guide for more.

Cut single layer when possible

Cutting through folded knit fabric can shift the layers and produce mismatched pieces. Cut single layer for accuracy, especially on larger garments.

Don’t pull the fabric while cutting

Let the fabric lie naturally. Pulling it taut to cut produces pieces that “snap back” smaller than intended.

Sewing the basic seam on knit fabric

The standard knit seam:

Place the fabric pieces right sides together.
Pin in the seam allowances every 5–8 cm.
Sew with a narrow zigzag (1.5 mm × 2.5 mm) or stretch straight stitch.
Don’t pull the fabric while sewing. Let the feed dogs work. Light guidance with both hands keeps the fabric flat without stretching it.
Press the seam to one side (not open, on knits — open seams curl).

The seam should stretch when you stretch the fabric. Test on a scrap before committing to the actual project.

Finishing seam edges

Knit fabric doesn’t fray, so finishing isn’t strictly required. But the cut edges curl, which can look untidy on the inside.

Options:

Don’t finish

For knits that lie flat (ponte, sweatshirt fleece, scuba), unfinished seams are fine. The fabric doesn’t fray; the inside of the garment is rarely visible.

Zigzag the raw edges

Run a zigzag stitch along each cut edge to lock it in place and prevent curling. Quick and effective.

Use a serger

If you have a serger, it’s the textbook solution. A 3-thread overlock along each seam allowance edge produces a ready-to-wear-quality finish. Our serger buying guide covers whether you need one.

Hemming knits

Hemming knits is where home sewers most often go wrong. The classic problem: a hemmed knit garment that ripples along the hem because the stitch couldn’t stretch with the fabric.

The standard solutions:

Twin needle hem

A twin needle has two needles attached to a single shank. Stitching with a twin needle produces two parallel rows of straight stitching on the right side, with the bobbin thread zigzagging between them on the wrong side. The bobbin’s zigzag gives the stitch enough stretch to flex with the fabric.

To use:

Insert a 4 mm or 6 mm twin needle (the number is the distance between the two needles).
Thread one needle from each of two thread spools (most machines have a second spool pin or a way to stack two spools).
Hem the garment by folding once toward the inside (no double fold needed on knits — they don’t fray) and stitching with the twin needle from the right side.
The result: clean parallel rows on the right side, stretchy zigzag on the wrong side.

This is the closest a home sewing machine gets to a ready-to-wear knit hem.

Cover stitch machine

A cover stitch machine produces the same effect as a twin needle but built more robustly — typically two or three rows of top stitching with a serger-style underside. If you sew lots of knit garments, a cover stitch machine is the next purchase after a serger.

Zigzag hem

Less polished than twin needle but functional. Fold the hem once toward the inside, then sew a zigzag stitch from the right side. Works for casual T-shirts and PJs.

Hem tape (knit-specific)

Iron-on knit hem tape can be applied inside the hem before stitching to add stability and prevent stretching. Useful for tricky fabrics.

Necklines on knit garments

Knit necklines are typically finished one of three ways:

Self-fabric band

A short strip of the same knit fabric, joined into a circle, slightly smaller than the neckline opening. Stretched gently and sewn around the neckline. The band’s elasticity pulls the neckline flat against the body.

Standard for T-shirts, sweatshirts, and most casual knit tops.

Ribbing

A different knit fabric (cotton ribbing) used as the neckband. Stretchier and more recovery than the body fabric. Standard for sweatshirt necklines and athletic wear.

Bias binding (woven)

A strip of woven fabric (bias-cut) wrapped around the raw edge of the neckline. Less stretchy than knit binding; works for fitted necklines that don’t need to stretch over a head opening.

The pattern you’re using will specify which method. The most common (T-shirts) uses self-fabric or ribbing.

Assembling a basic T-shirt

A simplified order:

Sew the shoulder seams (one on each side) right sides together.
Apply the neckband: sew the neckband into a circle, fold it in half lengthwise (wrong sides together), then pin and sew it to the neckline opening with the band stretched evenly to fit.
Set in the sleeves: sew the sleeves to the armhole edges (right sides together, matching notches). Knit garments typically use a flat sewing method — sleeves attached to the bodice before the side seams are sewn.
Sew the side and underarm seams in one continuous seam from the cuff to the hem.
Hem the sleeves and the bottom of the shirt, typically with a twin needle.

The result: a T-shirt that fits like a real T-shirt. For the 25 beginner sewing projects path, the basic T-shirt is project 15.

Common knit-sewing mistakes

Stitches breaking when the fabric stretches

You used a straight stitch instead of a stretch stitch. Switch to zigzag, stretch straight, or twin needle.

Skipped stitches

Wrong needle. Switch to ballpoint or stretch.

Seams ripple along the length

You stretched the fabric while sewing. Don’t pull. Let the feed dogs work.

Hem ripples or stretches out

You sewed the hem with a regular stitch or stretched the fabric while hemming. Use a twin needle and don’t pull.

Pattern pieces shifted during cutting

Knit fabric is mobile. Pin in seam allowances only and use rotary cutter where possible.

Neckband sits awkwardly

The neckband length must be calculated carefully — typically about 80–90% of the neckline opening’s circumference, depending on fabric stretch. The pattern will specify; if you’re going pattern-free, test with scrap.

Practising on scrap

Cut two 15 × 30 cm rectangles of knit fabric. Sew them together along one long edge with a narrow zigzag. Then test:

Stretch the seam — does the thread break?
Hem one short edge with a twin needle. Does the result lie flat?
Apply a small scrap as a “neckband” by stretching it to fit a curved edge.

Twenty minutes of knit practice on scrap teaches you most of the technique. Then you’re ready for a real T-shirt.

Closing thought

Knits frighten beginners because the fabric behaves differently from wovens. But once you’ve made the three adjustments — ballpoint needle, stretch stitch, gentle handling — knits are forgiving and fast. Most beginners who sew their first knit T-shirt successfully make several more in the next month. The genre rewards practice.

If you’re just starting with sewing in general, our complete beginner’s guide to sewing covers the fundamentals; once you’re comfortable with woven seams, knits become a natural next stage.