How wool keeps you warm

For decades if there has been one fiber to rule them all, it would probably be merino wool.

It’s incredibly soft.

It’s lush and luxurious.

And it has amazing properties that make it one of the most versatile textiles in the world.

Let’s take a moment to discuss what makes merino so magical, along with some picks for our favorite merino yarns.

We’ve already discussed why wool is a great for sweaters.

Just like a on sheep, the wool fibers act like a tiny micro-climate surrounding your skin.

The structure of the fibers allow its core to absorb moisture, while the scales on the outside help that moisture to bead up and run off.

This wicking property acts like an automatic sponge, keeping you both dry and warm.

And the high crimp of Merino wool also means it does not spin uniformly.

This creates tons of tiny air pockets between the fibers, allowing wool to trap more air around your body.

That barrier of air is what keeps the cold temperatures outside from affecting your skin too much.

It holds the heat of your body close to you helping you stay warm.

But Merino has another trick up its fleece…

The Magic of Microns

Microns are the thickness of fibers, and the smaller their count the thinner they can be spun. It also is a contributing factor in how soft the yarn will feel.

Luckily Merino is pretty darn small in the micron area.

That means that you can spin it very thin and it will also feel nice and soft against the skin.

These two factors are important for cold weather knits, because you can have a very warm sweater without it needing to be super thick.

But you can also spin thicker yarn which are more loosely spun, maintaining their drape and softness without being too bulky.

Merino Wool Yarns We Love

Here’s some of our favorite Merino wool yarns you might want to check out:

6-Ply Merino Wool by Gisimo

Aran Weight (CYC #4) | 100% Merino Wool (127yds / 50g)

Looking for crisp cables and smooth, even fabric? This 6-ply merino has a round, balanced build that gives stitches extra definition and bounce, with the softness you want for next-to-skin sweaters, hats, and everyday accessories.
Get it at Amazon
Modish Merino by KnitPicks

DK Weight (CYC #3) | 100% Extra Fine Merino Easy Wash Wool (256yds / 100g)

If you want stitches that really pop without babying your project, this springy 3-ply delivers soft bounce and clean definition. It uses an enzyme-based easywash (no chlorine), so you can toss it in a cool, delicate cycle and keep that natural wool feel. Perfect for heirloom sweaters and everyday knits alike, with 28 shades for that perfect color pick.
Get it here
220 Superwash Merino by Cascade

Worsted weight (CYC #4) | 100% Superwash Merino Wool (220yds / 100g)

This yarn is a buttery soft worsted-weight Merino heaven! Part of the Cascade 220 family, this 100-gram hank is machine washable and available in dozens of bold shades ranging from bright jewel tones to deep earth tones! With 220 yards to each hank, this yarn is versatile and perfect for all projects, both big and small!
Get it here
Muse by Knit Picks

Aran weight (CYC #4) | 100% Superwash Merino (114yds / 100g)

Hand-painted in Japan, this superwash Aran single-ply is firmly twisted for stability and even thickness, giving you soft drape without the usual splitting or pilling—and it’s machine washable. The dense twist knits into a satisfying, substantial fabric for hats, cowls, and statement sweaters. Artisans blend just three base dyes to create rich, streak-resistant colorways; tonals read almost solid, spotlighting cables and textured stitches.
Get it here
Worsted Merino by Malabrigo Yarns

Worsted weight (CYC #4) | 100% Merino Wool (210yds / 100g)

Malabrigo Worsted Merino is an incredibly soft and squishy hand-dyed yarn - it's a guaranteed favorite! This yarn is offered in Malabrigo's famous kettle-dyed color palette, making it versatile and fun for all projects whether you want a vibrant solid or variegated neutral, Malabrigo's got your back! With beautiful stitch definition and texture, you can't go wrong with Worsted Merino!
Get it here