Balls of Yarn with Knitting Needles

Yarn for Knitting Projects: Fibers and Weights Explained

Written by: Allyson Carmody



Time to read 5 min

"Don't you have yarn like that already?" If we each had a dollar every time someone asked us this question, we could each build a lovely cottage surrounded by beautiful flowers and butterflies to store all of the gorgeous, squishy yarn we could afford with all that money. Ah, dreaming…

So, let’s answer this question that most of us have been asked at least several times… “don’t you have yarn like that already?” Or maybe it’s asked in another variation, such as – “don’t you have yarn that color already?” I can’t even count how many times my husband has asked me these questions. He really should know better.

Well, the answer is that actually, no, I don’t (okay, or probably don’t. Maybe. Heh). The reason is, of course, that we use different types of yarn for different types of projects. So, let’s talk about some of the different types of yarn.

I will go over the basics here. There is so much to write about fiber, but I will stick to the essentials and most common fibers on the market so you have a good overview of the subject.

When selecting yarn for a project, it's important to consider two main factors: fiber type and fiber weight. The type and weight of fiber determines the characteristics and performance of the yarn, along with the overall look of the finished project. By carefully evaluating these aspects, you can ensure that your choice of yarn is a good fit for your project requirements and enhances your knitting experience.

Fiber Types

There are three main categories of fiber types for yarn. These are protein (animal) fibers, plant fibers, and synthetic fibers. Let’s take a look at the most common sources of fiber that you’re most likely to come across in these categories.

Protein Fibers

The first fiber type we’ll review is protein fibers. These are fibers that come from animals.

WoolSheep in Field

Wool comes from sheep. What kind of sheep? Oh, just a few different types. Among them are Icelandic, Rambouillet (when referring to the sheep, it is pronounced “ram-buh-lay”), Bluefaced Leicester (pronounced like “Lester”), Suffolk, Romney, Southdown, Rough Fell, Columbia, Perendale, Corriedale, Shetland, and Merino. Superwash Merino is wool that has been specially treated so that it is machine washable.

Wool is flame-retardant and water-repellent. It absorbs moisture and then releases water vapor. In fact, it can absorb moisture up to 30% of its weight, and yet not feel wet. It generates heat as it absorbs moisture, so it keeps you warm and comfortable.



There are two types of alpaca – Huacaya (pronounced “wah-kai-uh”) and Suri. Huacaya make up 90% of the alpaca population. Alpaca is water-repellent, strong, and has varying colors of fleece. Baby alpaca yarn is extremely soft.


Mohair comes from the Angora goat. Mohair is flame-retardant, moisture-absorbent, warm, and strong.


This comes from the Cashmere Goat. Cashmere is moisture-absorbent, warmer than sheep’s wool, light, fine and soft, and durable.


Angora Rabbits

When we talk about Angora yarn, keep in mind that it comes from the Angora rabbit…not to be confused with the Angora goat that produces mohair. Angora is very light and retains heat exceptionally well. It is warmer than wool. It also has a superb moisture-wicking quality, and is fine, soft, and durable.


This luxurious fiber comes from silkworms. There are two types of silk – Bombyx mori (often called mulberry silk), which is white; and Tussah silk, which varies in color from off-white to honey brown. Bombyx mori (mulberry) silk is softer and finer than Tussah silk; Tussah silk is stronger and coarser than Bombyx mori. However, both are extraordinarily strong, light, smooth, warm, and similar to wool in moisture absorption/release abilities.

Plant Fibers

Next up are the fibers produced by different plants. Some of the most common on the market are cotton, linen, and bamboo.



Cotton, which comes from the cotton plant, is durable, strong, soft, and breathable, so it is great for hot weather. A couple of types of cotton used to produce yarn are Pima and Egyptian.

LinenFlax Plant

Linen comes from the flax plant. It is very durable (stronger than cotton) and it quickly absorbs and evaporates moisture. It’s great for keeping cool in hot weather. On the flipside, linen fabric is notorious for easily getting wrinkled.


Bamboo comes from the bamboo plant. It is softer than cotton; and like linen, it quickly absorbs and evaporates moisture, so it is also comfortable for hot weather.

Synthetic Fibers

And last, but not least, are synthetic fibers. The two most common are acrylic and nylon.  


Acrylic is soft, lightweight, machine-washable, and fast-drying. In addition, it is resistant to moths and doesn’t shrink. Acrylic yarn also comes in a very wide variety of colors.


Nylon is remarkably strong. It’s also lightweight and easy to wash. However, it does not absorb water (so this can cause discomfort under certain circumstances). You might also see this listed as polyamide. Nylon is usually added to other types of yarn to provide more durability. In fact, a common yarn blend is superwash merino and nylon.

Now that we have looked at the very basics of fiber types, let’s learn about the other factor you need to consider when choosing yarn for a project, and that is the yarn weight.

Yarn Weights

Different projects require different weights of yarn. What does weight mean when it comes to yarn? Well, basically, it’s how thick the yarn is. You don’t want to use a bulky weight for a lace shawl or worsted weight if the pattern calls for fingering weight. Each yarn weight corresponds to a number. The higher the number, the thicker the yarn. The thicker the yarn, the larger the needle size you need. Your knitting pattern will tell you which weight of yarn and what size needle you need for your project.

Below are the yarn weights, along with their corresponding numbers, and a handful of ideas of some things you could create with each.

0– Lace: Lace weight yarn can be used for items such as very lightweight cowls, shawls, scarves, or even home décor, such as doilies.

1 – Super Fine (sock, fingering): Use this yarn to create socks or baby clothes. You can also knit lightweight cowls, shawls, scarves, or home décor, such as doilies.

2 – Fine (sport): This yarn weight can be used to make socks or baby clothes, lightweight cowls, shawls, and scarves.

3 – Light (DK, light worsted): You can use this to knit socks or baby clothes. You can also make lightweight cowls, shawls, and scarves.

4 – Medium (worsted, aran): In the U.S., this is very commonly called “worsted weight,” though the tag on the yarn you buy might say “medium.” Worsted weight yarn can be used to knit a multitude of items, such as cowls, shawls, scarves, mittens, washcloths, dishtowels, and sweaters.

5 – Bulky (chunky): Bulky yarn can be used to create things such as winter hats, chunky scarves, cuddly blankets, cozy sweaters, and mittens.

6 – Super Bulky (super chunky): Try this yarn weight for knitting items such as winter hats, a bit chunkier than chunky scarves, or cuddly blankets. 

Now equipped with this essential knowledge on yarn selection—understanding the intricacies of fiber type and yarn weight—you're primed to embark on your next knitting project with confidence and creativity. Happy knitting!

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