A Guide to Knitting Yarn: Types, Weights, and How to Choose It

When you're standing in the store before an arranged rainbow of yarn, how do you decide which one is perfect for your next knitting project? Here's everything you need to know beyond skim-reading the label.

Let's start with the basics: What is yarn? Yarn is a textile commonly made of either animal-based fibers (sheep's wool, mohair, angora), plant-based fibers (cotton, hemp, silk), or synthetic fibers (polyester, nylon, rayon). These interlocked fibers (referred to as plies) are spun together into thicker strands. The number of plies (for example, a single-ply yarn or two-ply yarn) will affect the drape, stitch definition, and general feel of the yarn. The ply count factors into the following categories:

Weight Categories

CATEGORY 0: LACE

(APPROXIMATE EQUIVALENT OF 1 PLY)

This is the lightest weight of yarn used for making doilies and other lovely lace designs. Therefore, treat it gently to avoid tangling or breakage.

CATEGORIES 1, 2, AND 3: SUPER FINE, FINE, AND LIGHT

(APPROXIMATE EQUIVALENT OF 2 TO 5 PLY)

This is suited for small items like socks, gloves, hats, or garments for babies and children. Cast on and off loosely. Specifically, fine yarn is commonly referred to as "sport weight."

CATEGORY 4: MEDIUM

(APPROXIMATE EQUIVALENT OF 8 TO 10 PLY)

Also known as "worsted," this is a popular weight among knitters of all skill levels because it provides great stitch definition in sweaters, scarves, hats, and mittens. Chunky stitches knitted in traditional Aran yarn of this weight can enhance the warmth of fiber.

CATEGORIES 5 AND 6: BULKY AND SUPER BULKY

(APPROXIMATE EQUIVALENT OF 12 TO 14 PLY)

Materials of this weight produce fast projects on big needles. Think: chunky scarves, throws, and blankets. This type of yarn is good for beginners because it produces projects quickly and is also good for advanced knitters who are looking to create something unique with novel yarn. Knit loose, large stitches for optimal loft. Unevenly spun yarn like boucled, chenille, or slubby yarn will produce uneven knits and a reduced stitch definition.

Common Fibers

WOOL

Spun from the fleece of sheep and one of the most popular yarns, wool is accessibly priced and easy to handle. It works well for knitwear garments in both the winter for its durability and resistance to moisture as well as the summer for its breathability and moisture-wicking. It's often mixed in a blend with other fibers to improved durability. Naturally, wool is a creamy white and therefore can be dyed a range of colors. Unfortunately, wool is prone to pilling over time.

Care: Gently hand wash in tepid water.

MOHAIR

This fluffy, luxurious fiber is known for its soft sheen and lightness despite being one of the warmest animal fibers. It is more expensive than wool. Mohair is very elastic-stretching and springing back to shape so it resists wrinkling and sagging. Because it is so fluffy, it can be hard to knit-especially if you want defined stitches. It is often blended with silk or wool to add weight. It can also irritate the skin causing itchiness despite having a low-allergenic risk.

Care: Dry-clean or machine wash on gentle cycle.

COTTON

This is a natural plant fiber and one of the most common. It is fairly inexpensive. Because it is so smooth, it's great for showing off complicated stitchwork. It has great drape, however it is inelastic and prone to splitting in the middle of your knitting.

Care: Machine washable.

CASHMERE

Due to its superb quality, this is a true luxury yarn. Softness actually improves with wear. Because of its superior insulation, it is well-suited for winter cardigans and accessories. Not to mention, it is beautiful-associated with a fine cloudlike halo. It is typically blended with other fibers to make the cost more accessible. It does not breathe as well as other natural fibers, although you can stitch loosely to accommodate this, and is prone to pilling.

Care: Dry-clean.

ANGORA

This comes from the fur of the angora rabbit. One of the finest animal fibers, it is light, silky-soft and incredibly warm (it is even seven times warmer than sheep's wool). A true luxury yarn, it is one of the most expensive. Akin to mohair, angora isn't great for knitting ornate stitches and tends to be slippery, so choose a textured set of needles for grip. It does not resist stains well although it does resist retaining odors. It is blended with an acrylic fiber to counter its elasticity.

Care: Must be dry-cleaned or hand washed in cold water, then laid flat to dry.

ALPACA

Spun from the fleece of alpaca, this dense fiber is hypoallergenic, making it a good option for those with sensitive skin, particularly for baby knitwear. This fiber has a strong tendency to overdrape, so it's blended with other natural fibers to strengthen the tension.

Care: Dry-clean or gently hand wash.

SILK

Obviously, this fiber is "silky" smooth and lustrous. This is most accessible in fine plies because it is a more expensive fiber. While great for knitting lace, it is susceptible to static cling and catching. To counter this, we suggest choosing a variety that is spun tightly with a higher ply. Silk is often blended into other fibers to add luxurious softness.

Care: Dry-clean or gently hand wash.

RAYON

This is the oldest man-made fiber that can nonetheless imitate the properties of natural fibers-it is shiny, silky smooth, and saturated in color with incredible drape. Because it is cool, comfortable, and conducts heat from the body, it makes a perfect yarn for summer knitwear. On the other hand, it doesn't retain warmth well, have elasticity, or age well over time. Typical varieties include textured novelty yarn like boucle or ribbon.

Care: Can be hand washed, but check the label for washing instructions to be sure.

NYLON

This is a synthetic fiber originally manufactured to offer an alternative to silk. Akin to rayon, it is smooth and shiny, easy to launder, and cool to the touch. However, it is very durable against wear and tear.

Care: Mashine washable.

POLYESTER

Polyester blends with natural fibers to yield easy-care yarns. This yarn type has good draping, along with wicking and breathability qualities-making it appropriate for any season in the year. However, it can feel scratchy against the skin and doesn't show stitch definition well.

Care: Machine washable.

Understanding the Label

Each yarn has a the label, which states everything you need to know including the fiber content, weight, amount, care instructions, suggested needle size, gauge, and dye-lot number.

Fiber content: This is the material of yarn, often in percentages. (For example, 90 percent merino wool, 5 percent alpaca, and 5 percent cashmere.)

Weight: This is the total thickness of yarn, often measured in wraps per inch (WPI). The ply count also factors into it and ranges from the finest to the heaviest weights (usually between 1-ply and 14-ply). Currently in the United States, the categories range in accordance to these symbols.

Amount: This is the total length of yarn, measured in yards and ounces.

Care instructions: This provides the necessary information on how to wash and dry your knitted garment.

Suggested needle size and gauge: Yarn gauge is specified by the number of stitches and rows.

Dye-lot number: This refers to the color of yarn. When buying in multiples, be sure that the numbers match. Even when two balls of yarn appear to be the same shade, the subtle difference can become clear in the final knitted garment.

In the end, choose the yarn that is best suited to your project. Often, the instructions will suggest the right weight yarn and needle size to use. But when you're knitting something of your own invention, stop to consider: Do you want this item to be machine washable? Is it meant to breathe in hot weather or keep you warm in the cold? What is the size and shape of the item? A sturdy merino wool will make a well-made pair of winter mittens, while a loopy rosette scarf is made sumptuously soft with a luxurious material such as mohair. It's entirey up to you to craft the perfect knit piece.

Feeling inspired? Watch how to arm-knit a giant blanket with super bulky yarn: