Sweater Knit Fabric: Types and How to Sew Them

Sweater knit fabric is what Shannon calls "instant" sewing — simple pattern pieces, fast projects, and results that look far more difficult than they were. But "sweater knit" covers a wide range, from firm stable boucles to light two-way-stretch knits, and the right needle and stitch depend on which you have in front of you. This guide covers all three weights, how to tell them apart, and how to sew each, with expert tips from sewing instructor Shannon Gifford.

What is sweater knit fabric?

Sweater knits are incredibly versatile. Depending upon the amount of stretch in your knit, you can use the fabric for patterns specifically for knits, or you can choose some patterns for wovens. These knits are simple to sew, easy to care for, and give great results!

The three weights

Stable sweater knits are firm with little stretch, often boucle-textured. Great for quick projects, but don't be afraid to use them in more detailed projects.

Close knits with drape are firmly knit while retaining some drape. These are among the easiest of knits for sewing — the fabric has stability, which makes sewing a breeze, and they are comfortable and flattering to wear.

Lightweight and stretchy sweater knits have two-way stretch and are light to medium weight. You'll be surprised at the ease of sewing when you try these knits.

Check the stretch gauge first

Some sweater knits have moderate stretch from selvedge to selvedge. Some have very little stretch at all. Because of this variety, check the stretch gauge on the back of your pattern before using your fabric. Your fabric should stretch the recommended amount in order to be successful in the project.

Unless the fabric has more than moderate stretch — in which a 4 inch length of fabric stretches to at least 7 inches — do not use it for form-fitting patterns.

Pretreatment

Treat your fabric as you would treat a purchased sweater. The boucle-type knits will sometimes machine wash successfully; test your fabric for shrinkage before cutting out your project. If you do experience shrinkage, plan to hand wash your finished garment.

Do not machine wash coats or jackets with fused interfacing or extensive detailing such as trims, heavy buttons, or linings. Instead, plan to dry-clean more detailed garments. For lighter stretchy knits, hand-washing and laying the garment flat to dry are the safest options.

Needles and thread — match to your weight

Stable knits: the size needle depends on the thickness of the knit. Start with a 75/11 or a 90/12. The more textured, boucle-type knits can be stitched with a universal needle; for less textured, smooth-surface knits, use a stretch needle.

Close knits with drape: use a jersey/ballpoint needle, size 11.

Lightweight and stretchy: use an 80/12 stretch needle.

For all three, cotton-covered polyester or all polyester threads are good choices. If you can find silk thread to match your fabric, use it for surface thread finishes such as hems, for a beautiful luster.

Seams, seam finishes and hems

Stable knits: choose a wide zigzag, 2.0 length and 2.5 width, to work with the stretch and texture. You will want to finish the seams in this fabric, as it tends to ravel if left unfinished. Use a fold-over tricot (Seams Great is one brand), a 3-thread balanced seam finish on the serger, or bias strips of lightweight fabric to bind the seam allowances.

Close knits with drape: a serger makes quick work of these — use a three or four thread balanced stitch for construction and seam finishes. Without a serger, use a small zigzag, approximately 2.0 length and 2.0 width, to let the fabric keep its stretch. Hems can be topstitched with a ballpoint twin needle, or use a coverstitch.

Lightweight and stretchy: choose a medium width zigzag, 2.0 length and 2.0 width. A 3-thread overlock with balanced tension works beautifully. Most will need a seam finish — a 2 or 3 thread serger stitch on the edge, or a 2.0 length by 3.5 width zigzag over the edge before construction. Press afterwards to ease out any distortion the stitching caused; steam will take care of it.

A twin-needle hem is not necessary in the lightweight knits — the stitching will be lost in the texture. Simply clean-finish the edge, turn under the hem, and zigzag it in place. A flat-lock hem on your serger works well too.

Interfacing

For stable knits, try Fusi-Knit for less structured garments such as cardigans and loosely fitted tops, and Whisper Weft for semi-fitted jackets or coats. For close knits with drape, fusible knit tricot cut to match the stretch of the fabric is preferred. For lightweight knits, choose something light such as So Sheer or Fusi-Knit.

If your sweater knit is textured, place a terrycloth towel on the ironing board and lay the fabric face down on it before fusing, to stop the texture crushing. Match the grain of your interfacing to the grain of the knit. If you are adding surface trim, add a strip of interfacing one inch wide around the inner perimeter of the trimmed edges to support the embellishment.

Buttonholes and closures

Beautiful buttonholes are possible in sweater knits with careful planning. Test on a scrap first. Begin by stabilizing the area under the buttonhole with interfacing — for most sweater knits, the same interfacing used for the rest of the garment is the best choice.

If you can change the density of your buttonhole stitches, use a less dense satin stitch. Cord the buttonhole by placing a few strands of ravelled fabric yarns in the stitching. You can also make bound buttonholes; if your knit is heavily textured, use a thinner fabric in a complementary color for the lips, and interface around the opening.

Another option is covered oversized snaps. Purchase snaps half an inch wide or larger and cover them with thin lining fabric. This is an elegant solution seen in many very expensive garments. Zippers are not good choices for closures on most stretchy sweater knits.

Choosing a pattern

Anything that looks like a commercial sweater is a good choice. Cardigans, turtlenecks, tees, tanks, skirts, dresses, hoods, capes, shawls, and twin sets all work. Most stable sweater knits work best as cardigan or jacket styles; ponchos, capes and scarves are other possibilities, and a stable knit makes excellent covers for home décor pillows.

Avoid horizontal darts, intricate pattern pieces, patterns with very small inserts, and anything very body-conscious.

Weighting a hem

Occasionally you may need to weight the hem of a sweater-knit garment to let it hang properly. Pad the hem slightly with interfacing or a bias-cut layer of soft fabric like flannel, basted into the hem allowance before stitching. Or hem the garment with a facing and add a decorative chain one inch from the fold on the inside — particularly elegant for jackets and cardigans.

Making a tailored sweater jacket

1. Choose a lightweight knit or bias-cut woven for the undersides of collars, lapels, cuffs and hems to reduce bulk.

2. An underlining of mesh knit, tricot, or stretch woven will add to the longevity of your garment.

3. Use a slightly heavier weight interfacing for the shoulder. Whisper Weft is good here. Cover the interfacing with a half-lining.

4. For a ready-to-wear look, use velvet for the collar, cuffs and lapel. It's a beautiful combination.

Creative possibilities

Pair your knits with leather or wool felt accents. Make a traditionally shaped short jacket trimmed with velvet or piping — boucle-type stable knits pair beautifully with quilted strips of denim matching the base color.

Use a fun yarn as trim: run a row of wide zigzag parallel to the cut edge for stability, then crochet two rows of single crochet catching both fabric and stitching with an eyelash yarn. Don't crochet? Lay three strands of yarn a quarter inch from the edge and secure with a blind hem or wide zigzag stitch.

Make leg warmers from your knit, trimmed with matching ribbing. Depending on the knit, you may be able to unravel some yarns and twist them together for perfectly matching cording.

Pressing and handling

Use your iron's steam without pressure. Hover the iron about half an inch above the fabric and let the steam permeate, then remove the iron and gently finger-press the damp fabric to set the press. Allow it to cool completely before moving it.

Use a terry-cloth towel on your pressing surface to protect the texture from crushing, with a press cloth and lots of steam. Keep a vacuum cleaner handy as you cut — the more textured knits shed.

Related guides

New to knits? Start with the warm up to sweater knits series, which covers seaming and alternatives to ribbing in detail. For related knits, see scramble knit, tube knits and eyelash knit. Or, an unlined jacket for comfort and style.

Shop sweater knit fabric

Browse the sweater knits collection at EOS. Back to all fabric care guides.

FAQ

What is sweater knit fabric?

A knitted fabric with the weight and texture of a commercial sweater, ranging from firm stable boucles with little stretch to light two-way-stretch knits.

What needle do you use for sweater knits?

It depends on the weight. Stable knits: 75/11 or 90/12, universal for textured boucles and stretch for smooth surfaces. Close knits with drape: ballpoint size 11. Lightweight stretchy knits: 80/12 stretch.

How do you stop sweater knit seams stretching out?

Use a zigzag rather than a straight stitch so the seam moves with the fabric, and finish edges on stable knits, which ravel.

How do you check if a pattern suits your sweater knit?

Use the stretch gauge on the pattern envelope. If a 4-inch length doesn't stretch to at least 7 inches, avoid form-fitting styles.

Can you make buttonholes in sweater knit?

Yes. Interface underneath, use a less dense satin stitch, and cord the buttonhole with strands of the fabric's own yarn. Bound buttonholes and covered oversized snaps also work well.

How do you press sweater knits?

Never with pressure. Hover the iron half an inch above, let the steam through, finger-press, and let it cool completely before moving it.