With endless yarns to choose from, it can be hard to pick the right one for your next project! There are two key factors to start with when choosing a yarn: fiber and weight. But what are the different fibers and weights a knitter might use, and how does one go about choosing which are best for a project? A little education mixed with a little hands-on practice is all it takes, and below we’ve got all the information you need before you’re ready to start casting on.

The Most Common Yarn Fibers

The Most Common Yarn Fibers

When talking about textiles, fibers are the materials that get spun to create yarn, and they can come in a variety of forms from a variety of sources. Knowing which fibers are best suited for this or that will help you create projects you love everytime, whether you’re substituting yarn in a pattern or planning from scratch. Different fibers behave differently, so no matter how skillfully the stitches are knit, the fibers used have a heavy influence on the overall look. Knitting fibers are typically broken into three categories—animal fibers, plant fibers, and synthetic fibers—because this makes it easy to avoid allergens, but there are other key factors to keep in mind such as care and the ideal season to wear each fiber. We’ve included each of these details and more for the most common fibers you’ll find on KnitPicks.com.

Animal Fibers »

Fiber: Wool

Ideal Season: Fall, Winter, Spring

Care: Hand wash cold and lay flat to dry

Favorite Yarns: Wool of the Andes, Palette

Wool is a fiber that comes from sheep, and it’s the classic choice for hand knitting. Wool has a reputation for being warm, and it also wicks moisture and has a unique fiber structure that allows it to remain warm even when soaking wet. Wools with more crimp and thickness to the fiber, such as our beloved Peruvian wool, are incredibly hard wearing, but wools can also be decadently soft and delicate, like Merino, which is explained in more detail below. Wool makes lovely cables, lace that can be precisely blocked, and beautiful simple stitches. It also grips to itself, which makes neat colorwork achievable with less effort, allows for steeking, and makes unintentionally dropped stitches easier to get back on the needle. Wool can also be felted to create a dense, solid, structural fabric.

Wool
Merino Wool

Fiber: Merino Wool

Ideal Season: Fall, Winter, Spring

Care: Hand wash cold and lay flat to dry

Favorite Yarns: High Desert, Swish, Stroll

Merino is a specific breed of sheep that is famous for its incredibly soft fleece. It’s one of the softest wools on the market, and it’s considered a luxury wool. Many people who find other wool scratchy can happily wear Merino wool. Like most extra soft fibers, Merino can pill, or form balls of fluff, when it’s frequently worn due to the shorter length of those fibers, so it’s not recommended for pieces that will be put to heavy use like a fisherman’s sweater, but for everyday knits, this is easily solved with a sweater shaver or by choosing a Merino blended with a stronger fiber like nylon. Aside from not being as hard wearing as less-soft wools, Merino shares all the attributes listed above for wool.

Superwash Wool

Fiber: Superwash Wool

Ideal Season: Fall, Winter, Spring

Care: Machine washable

Favorite Yarns: Swish, Wool of the Andes Superwash, Stroll

Superwash wool is wool that has undergone a special process to either strip the natural scales from the wool or permanently secure them down so that the wool can no longer be felted. This creates a wool that has a slightly slicker feel as well as a softer drape than natural wool and can go in the washing machine. In addition to the added convenience, it maintains its wicking properties as well as the lovely stitch definition, ability to block lace, and bouncy cables. Superwash wool does occasionally stretch, particularly when allowed to hang while wet, but it typically returns to its prior shape after being dried in a dryer until it's barely damp and then reshaped and allowed to dry flat.

Alpaca

Fiber: Alpaca

Ideal Season: Winter

Care: Hand wash cold and lay flat to dry

Favorite Yarns: Andean Treasure, Alpaca Cloud, Wonderfluff

Like you might guess from the name, alpaca fibers come from the alpaca animal! One of the warmest natural fibers available, alpaca fibers have a hollow core that helps hold in even more warmth! It’s also incredibly soft, making it one of our favorite choices for winter accessories that sit close to the skin, like scarves or hat linings. It’s graded by the size of the fiber, and the smaller it is the softer! The finest rating of alpaca is called baby alpaca, and the next finest rating is superfine. Both of these ratings are true luxury fibers. Like wool, alpaca fiber can felt, so it needs to be washed with care, but it differs from sheep’s wool in its drape and elasticity. Alpaca has low elasticity and an elegant drape, making it a great choice for lace pieces. Alpaca yarns also tend to bloom, or fluff up with a very slight halo, after being blocked, which can enhance the look of lace stitches.

Cashmere

Fiber: Cashmere

Ideal Season: Winter

Care: Hand wash cold and lay flat to dry

Favorite Yarns: Capra DK, Capretta

When imagining luxury fibers, cashmere often comes to mind! This fiber comes from the soft undercoat of the cashmere goat, and the small, fine fibers are naturally incredibly soft. Because the fibers are so fine, cashmere yarn is delicate and can develop pills—balls of fluff on the surface of a knit—if not carefully cared for, but the luxury of cashmere makes it worth the special attention it requires! Use cashmere for accessories that will be treated gently, like scarves or hats, or plan to use a sweater shaver, which will help to remove pilling. Alternatively, try a cashmere blend! Blending cashmere with other fibers like nylon and wool adds strength without sacrificing softness or the look of cashmere. Both cashmere and cashmere blends bloom after washing, creating a light halo and a supremely soft, warm fabric.

Mohair

Fiber: Mohair

Ideal Season: Fall, Winter, Spring

Care: Hand wash cold and lay flat to dry

Favorite Yarns: Aloft

Long, crinkly fibers give mohair its unique look! This fiber comes from the Angora Goat—not to be confused with the Angora Rabbit that gives us angora yarn—which has a crimped, curly coat. Mohair is typically spun in such a way that the long, wavy fibers are loose enough to create a beautiful halo. The fluffiest mohair yarns are often knit at a loose gauge to create an airy, sheer fabric with a fuzzy halo, but the same yarns can also be held double with a more solid yarn, like a Merino yarn, to add a halo to a solid fabric. Because most mohair yarns are extremely fluffy, it can sometimes stick to itself while knitting, making ripping back knitting or untangling a section of yarn challenging, but freezing mohair helps the fibers relax so they can be separated more easily. Finished knits made with mohair can be brushed to enhance the fuzzy look even more.

Silk

Fiber: Silk

Ideal Season: Fall, Winter, Spring, Summer

Care: Hand wash cold and lay flat to dry

Favorite Yarns: Luminance, Gloss

Known for its stunning sheen, high tensile strength, and warmth, silk is a beautiful fiber on its own or when combined with other fibers for luxury blends. Harvested from silk cocoons, the strands are then spun into silk thread and yarn. Despite having such a delicate feel and appearance, silk fibers are long, incredibly strong, and produce quite a bit of warmth when worn. They have a beautiful finish and shine to them that stands out even when blended with other fibers, like wool. Although silk is incredibly strong when dry, wet silk fibers are delicate and can break or lose their luster, which is why it's recommended to wash silk by hand and lay it flat to dry.

Plant Fibers »

Fiber: Cotton

Ideal Season: Spring, Summer

Care: Machine washable

Favorite Yarns: Dishie, Comfy, Shine

Cotton is the most well-known plant fiber and one of the most popular fibers to knit with next to wool. It’s a durable, breathable fiber that’s incredibly versatile, making it an equally great choice for hard-wearing dishcloths and light summer tops. After the initial shrink, cotton can be washed on hot water and come out looking just as great as it did before, which is why it’s a favorite choice for homegoods. It creates crisp stitches with good definition, but cotton lacks elasticity—meaning when stretched, it stays stretched and does not snap back—so it’s not ideal for ribbing or fitted garments. Cotton is often blended with other fibers, like wool, acrylic, or viscose, to add in some elasticity.

Cotton
Mercerized

Fiber: Mercerized Cotton

Ideal Season: Spring, Summer

Care: Machine washable

Favorite Yarns: Animation, Curio

Shine and luster are added to cotton through a chemical treatment called mercerization to create mercerized cotton, also known as pearl cotton. The mercerization process smoothes the outer layer of the cotton fibers, which creates an incredible sheen and also allows the mercerized cotton to absorb more dye and shed less lint. The one drawback to mercerized cotton is that it’s less absorbent than regular cotton, so it’s not well suited to dishcloths or washcloths. Except for being less absorbent, mercerized cotton shares many of the same properties of regular cotton, like being able to be washed on hot, breathability, low elasticity, and good stitch definition. Mercerized cotton is a popular choice for toys, thanks to its ability to be dyed bright, saturated colors, and it’s also frequently used for lace doilies.

Linen

Fiber: Linen

Ideal Season: Spring, Summer

Care: Machine washable

Favorite Yarns: CotLin, Lindy Chain

Linen is one of the oldest plant fibers still commonly used, and it comes from the flax plant, which also provides flax seeds. Linen is best known for its breathability and sweat wicking properties for garments, but it’s also a great choice for homegoods like washcloths because it dries even faster than cotton. Much like cotton, linen can shrink initially when washed with hot water, but once shrunk, it can hold up to hot water. Often 100% linen can feel stiff and maybe even a little scratchy, but as it’s worked with, used, and washed, it becomes softer and softer, eventually becoming irresistible to touch. Linen is the perfect fiber for heirloom projects because of how it softens with age, but linen blended with other fibers like cotton allows knitters to enjoy soft projects from the start, which will only get softer over time.

Synthetic and Processed Fibers »

Fiber: Acrylic

Ideal Season: Fall, Winter

Care: Machine washable

Favorite Yarns: Brava, Heatherly, Mighty Stitch

Acrylic is a synthetic fiber that’s typically produced to imitate the look of wool for handknitting. Lightweight and sturdy, it’s one of the best alternatives to wool for those that suffer wool allergies. It’s a great choice for cabled and textured projects, but as a man-made fiber, acrylic likes to consistently keep its original shape, so the way it looks on your needles is likely to be how it remains. This means that lace cannot be blocked open unless the yarn is set with steam, which ever so slightly melts the fibers and permanently alters their shape and texture.

Acrylic
Nylon

Fiber: Nylon

Ideal Season: Fall, Winter

Care: Machine washable

Favorite Yarns: Hawthorne, Stroll

100% nylon yarns are rare to see, but nylon is a staple of the knitting world thanks to its contributions to sock yarn blends! An early attempt at imitation silk, nylon is one of the strongest, flexible man-made fibers out there, and it helps to create yarns that can hold up to being walked on day after day. It also has a high amount of elasticity and dyes incredibly well, all attributes that make a handknit sock even nicer!

Rayon

Fiber: Rayon

Ideal Season: Spring and Summer

Care: Hand wash gently and lay flat to dry

Favorite Yarns: Shine, Samia

Rayons straddle the line between plant fiber and manmade. Natural cellulose that is too coarse to become yarn naturally, such as wood pulp or bamboo, is chemically broken down and reformed as soft, silky yarn in a process that was originally created to imitate the work of the silkworm. There are variations on the chemical process and cellulose sources used, which all have different names like Cupro, Viscose, Modal, and Lyocell, and each has a slightly different sheen and texture. Rayons stretch and break easily when wet, so they should be washed with care, but when dry, it’s a very sturdy fiber that both drapes well and maintains some elasticity. Much like silk and plant fiber yarns, rayon yarns create breathable knits with good drape, making rayon an ideal fiber for summer tops.

Yarn Weights Explained

Yarn Weights

Yarn weights indicate the thickness the fibers are spun into, and understanding yarn weights can help guide you to making the right choice to match the gauge of a pattern or create the project you’re dreaming of from scratch. Because different fiber types spun to an equal size yarn can weigh different amounts, the physical weight is not used to determine the yarn weight typically. Instead, either the wraps-per-inch or the average stockinette gauge of a solid fabric are used to determine the weight. At Knit Picks, we use the average stockinette gauge. A heavier yarn with fewer stitches per inch will make a thicker, bulkier project, and a finer weight yarn with more stitches per inch is best for lightweight garments and accessories. Referencing this guide will help you get the right density and drape in your next finished project!

Yarn Weights »

US Weight: Lace Weight

Weight Standard: 0

Also Known As: 2-ply, crochet thread, cobweb yarn

Average Needle Size Used: US 00–1 (1.5–2.25mm) for solid fabric, but typically larger needles are used for open lace

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 33–40 stitches

Typically Used For: Lace shawls, wraps, and stoles

US Weight: Fingering Weight

Weight Standard: 1

Also Known As: 4-ply, sock yarn, superfine weight

Average Needle Size Used: US 1–3 (2.25–3.25mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 27–32 stitches

Typically Used For: Socks, lace shawls, lightweight garments, lightweight accessories

US Weight: Sport Weight

Weight Standard: 2

Also Known As: 5-ply, baby yarn

Average Needle Size Used: US 3–5 (3.25–3.75mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 23–26 stitches

Typically Used For: Lightweight garments, lightweight accessories, baby sweaters, baby blankets, toys

US Weight: DK Weight

Weight Standard: 3

Also Known As: 8-ply, double knit weight, light worsted

Average Needle Size Used: US 5–7 (3.75–4.5mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 23–26 stitches

Typically Used For: Midweight garments, midweight accessories, toys

US Weight: Worsted Weight

Weight Standard: 4

Also Known As: 10-ply, afghan yarn

Average Needle Size Used: US 7–8 (4.5–5mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 18–22 stitches

Typically Used For: Midweight garments, midweight accessories, blankets, dishcloths, toys, homegoods

US Weight: Aran Weight

Weight Standard: 4

Also Known As: 12-ply, heavy worsted, fisherman’s yarn

Average Needle Size Used: US 8–9 (5–5.5mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 16–18 stitches

Typically Used For: Heavy garments, heavy accessories, blankets, homegoods

US Weight: Bulky Weight

Weight Standard: 5

Also Known As: 16-ply, chunky, craft yarn

Average Needle Size Used: US 9–11 (5.5–8mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 12–15 stitches

Typically Used For: Heavy garments, heavy accessories, blankets, homegoods

US Weight: Super Bulky Weight

Weight Standard: 6

Also Known As: Super chunky

Average Needle Size Used: US 11–17 (8–12mm)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 12–15 stitches

Typically Used For: Extra heavy accessories, statement knits

US Weight: Jumbo Weight

Weight Standard: 7

Also Known As: Roving

Average Needle Size Used: US 17+ (12mm+)

Average Stockinette Gauge Using Average Needle Size Over 4 Inches (10mm): 6 stitches over even fewer

Typically Used For: Dramatic statement knits

Choosing yarn to substitute in a pattern? Read more in our Guide to Substituting Yarn

Weight Standard Symbol Source: Craft Yarn Council's www.YarnStandards.com

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