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Yak Wool: The Ultimate Guide

Ideal for #repeat wear because of its comfort, durability, and antimicrobial properties.

Khullu (“coo-loo”) is the fine down a yak grows around its neck and belly to survive winters at 15,000 to 20,000 feet. Herders comb it out by hand each spring, never shorn. At around 17.5 microns it is soft like cashmere, and easy to care for, unlike cashmere: it goes in the washing machine.

A yak grazing open pasture below the mountains it evolved on, the animal khullu is combed from

Yak Wool, What’s So Special About It?

Odor-Resistant

Wear all the time. Our materials don’t trap odor.

Machine Washable

Easy to care for, while rarely needing a wash.

Soft

Our materials are similar in hand-feel to cashmere.

Breathable

More breathable than cashmere and lambswool.

Insulating

Yak naturally weather cold -40° F winters.

Sustainable

Far better for the planet than synthetics.

A yak herd crossing snow in single file, the winter half of an all-season fiber
The same herd on bare summer ground, the other half of the year the same coat has to cover

Yak Wool Is Perfect For All-Season Sweaters

Yak wool is versatile by evolution. Over thousands of years, yaks have evolved to survive and thrive in the unforgiving high-altitude climate of the Himalayas.

The Tibetan yak lives comfortably at 15,000ft - 20,000ft and is the highest dwelling wool-bearing mammal in the world. Extreme conditions have forced these magnificent beasts to grow some pretty remarkable fibers.

Khullu is some of the highest performing wool, we’d even go so far as to say it’s the world’s best wool.

The fiber is extremely durable while maintaining a soft and luxurious hand feel. Products made from yak wool last for decades, particularly if they’re manufactured properly (we 3D-knit ours).

The natural properties of yak wool make it ideal for repeat wear. That’s exactly why we use it in our go-to sweaters.

A herder beside his yaks at a summer camp, the partnership the fiber depends on
Two folded Oliver Charles sweaters side by side, the garment the fiber becomes

What Are Yak Wool’s Properties/Benefits

Wool comes in many different forms with different feels and functions.

Animals in the families of sheep, goats, yak, camel, and even ox produce a fiber broadly called “wool.”

All wool has crimps, which are little natural “waves’ in the fiber. These crimps are largely responsible for the amazing utility of wool.

  • Thermoregulation: As the highest dwelling mammals in the world, yak live through a big range of temperatures, and over time they developed hollow fibers in addition to crimps. The combination creates dynamic air pockets that regulate temperature, insulating yak in extreme colds and cooling them in extreme heat.
  • Antimicrobial: Yak wool is very antimicrobial, as sweat is absorbed from the skin’s surface it travels outwards where it evaporates. In the process, the yak fibers actively bind and isolate bacteria. The isolation of bacteria reduces odor to the point where unwashed khullu has 66% less odor intensity than plastic-based fibers and 28% less than cotton fabrics.
  • Moisture-Wicking: Wool can absorb and retain up to 35% of its weight in moisture and still feel dry to the touch, which reduces sweat buildup and discourages bacterial growth. Yak fiber is particularly good at this transporting moisture away from the skin 17% faster than pure sheep’s wool.
  • Durability: The crimps in wool are akin to a molecular coil spring. This allows wool fibers to be stretched up to 50% of their length when wet / 30% when dry and still bounce back to their original shape when stress is released.
A yak with its calf, the down layer being grown before it is combed out in spring
A yak head close up: coarse guard hair outside, the fine khullu underneath

Is Yak Wool Itchy?

No yak wool is not itchy.

One of the most important factors that affect the way wool feels is fiber fineness.

While human hair mostly falls between 50 and 100 microns (µm), the yak wool we use in our sweaters is ultra-fine at roughly 17.5µm.

Wools that are generally considered “soft” have a fineness <20µm. Fibers considered for use in cashmere clothing fall somewhere in the range of 14-19µm... so it depends, but generally, khullu is as soft as cashmere.

How fine is khullu?

Fiber diameter in microns. Lower is finer, and fineness is what makes wool soft.

  • Human hair 50 to 100 µm
  • Considered soft under 20 µm
  • Grade A cashmere 14 to 19 µm
  • Khullu 17.5 µm
Wool is considered soft below 20 microns. Khullu sits around 17.5, inside the 14 to 19 micron band Grade A cashmere occupies. It is as soft as cashmere, and more durable and more sustainable.
A yak in deep winter coat, the layer the micron figures above are measuring

How Does Yak Wool Compare To Others?

How does yak wool stack up against other materials such as sheep’s wool, cashmere, cotton, tencel, viscose, and other synthetics?

Yak wool compared with seven other fibers on six properties
Property Yak Wool Sheep’s Wool Alpaca Cashmere Cotton Tencel Viscose Polyester
Antimicrobial Yes Yes Yes Yes No Yes No No
Breathability Yes Yes Yes Yes Yes Yes No No
Thermoregulation Yes Yes Yes Yes No No No No
Moisture-Wicking Yes Yes Yes Yes No Yes No No
Durability Yes Yes Yes Yes Yes Yes Yes Yes
Sustainability Yes Yes Yes No No Yes No No
  • Yak Wool Vs Polyester: Everything beats polyester, the only benefit to synthetic fibers is softness. However, it comes at a cost, the fine synthetic fibers required to make a polyester soft shed into the water system with each wash and are the leading cause of microplastic pollution.
  • Yak Wool Vs Cotton: Khullu beats cotton in almost every way. it’s a far better thermoregulator and significantly more durable. While cotton might be breathable its poor wicking abilities cause it to retain odors.
  • Yak Wool Vs Alpaca: Yak wool and alpaca wool are both soft and popular for high-quality knitwear, and both are more environmentally sustainable than cashmere. Yak wool is generally more durable and resilient due to its higher tensile strength. Additionally, yak wool may be slightly warmer than alpaca wool because its higher crimp allows it to retain more heat, particularly in looser knit fabrics where air pockets enhance insulation.
  • Yak Wool Vs Sheep’s Wool: Yak and sheep’s wool are extremely similar, yak is almost like a super version of it. A little more antimicrobial, a little more thermoregulating, a little softer, and a little more expensive.
  • Yak Wool Vs Cashmere: Yak wool is often considered a sustainable alternative to cashmere. It’s soft like cashmere and easy to care for, unlike cashmere. It’s also 40% warmer and nearly 2x more breathable than sheep’s wool.
A yak standing on a bare ridge with snow-covered peaks behind it

How Sustainable Is Yak Wool?

Wool is naturally the most sustainable material to use when making clothing, it’s regenerative, biodegradable, and durable.

Yak plays a key ecological role within the regions they inhabit.

Besides recycling nutrients through their gentle manner of grazing and fertilizing dung, yak are central to human life.

They have partnered with nomadic herders for centuries.

Yak are gentle grazing animals meaning they have footsteps as soft as their khullu and short tongues that only remove the top of plants.

Other fiber-producing animals like cashmere goats pull up the grass by the roots, destroying the plainlands they inhabit.

Yak on the other hand lives nomadically throughout the mountains grazing by only removing the top of plants instead of their whole root.

Gentle grazing, nomadic lifestyle, and ecological contribution make yak fiber one of the most sustainable wools in the world.

How high on the Tibetan Plateau yaks live
20,000 ft
The winter cold their coat is built for
-40°F
The moisture wool holds by weight before it feels damp
35%
How much warmer khullu is than sheep’s wool
40%

A fiber that has to get an animal through a Himalayan winter turns out to be very good at getting a person through an ordinary one.

A yak head heavy with frost, the conditions the numbers above describe

Tibetan communities have been using yak wool for centuries.

However, the emergence of cheap durable synthetics has reduced its use to ceremonial garb only.

The demand for the luxurious wool has ebbed and flowed but has not caught on due to readily available alternatives such as cashmere, sheep’s wool, and alpaca, which are naturally white and therefore easier to dye than the naturally brown yak.

However, change is on the horizon, as the impact of overgrazing cashmere goats becomes more and more clear companies and consumers are looking for a sustainable alternative.

Yak wool compared with three other animal fibers on four measures of how they are produced
Measure Yak Wool Sheep’s Wool Alpaca Cashmere
Nomadic Herding Yes No Yes Yes
Gentle Grazing Yes Yes Yes No
Viable Herd Size Yes Yes Yes No
High Fiber Yield Yes Yes Yes No
A yak grazing beside a flock, healthier for having its winter down combed out

Does It Hurt The Yaks To Comb Their Fiber?

Every spring, yaks naturally shed fiber. The herders collect it by brushing the animals. Some fiber can also be hand-collected by herders as it sheds.

Yaks are healthier when their wool is combed out.

The process of gathering khullu helps yak keep cool leading into the 90°F summers. Yaks are kept by nomadic herders so they aren’t locked away in cages or confined to small pens.

Yaks in summer coat standing in green pasture below the mountains

Khullu And Other Types Of Yak Fiber

Yak grow three types of wool.

The first layer sits directly on the skin and is very fine.

This layer is often referred to as yak down or khullu and is what we use to make our sweaters.

The second layer of fur is known as the transitional layer. It’s coarser wool that may be used as insulation or combined with the topcoat to make various products.

The final layer is the topcoat, an extremely coarse canvas like wool used to make tents and ropes.

When woven tightly yak topcoat is waterproof.

A yak on bare frozen ground below snow-covered peaks

Where Does Yak Wool Come From?

Yaks live high up in mountainous regions of Tibet and Central Asia.

They have a long history dating back to the Pleistocene Period, which means that yak shared the land with the woolly mammoths, giant sloths, and short-faced bears!

Over the last 10,000 years, the vast population of wild yak has been domesticated.

Though domesticated, yaks still roam semi-wild with nomadic herders throughout the high passes of the Himalayas, the Tibetan Plateau, and the interior of Mongolia.

There is even a growing population of domesticated yak in the United States.

Products Made Of Yak Wool

The most common yak wool products are clothing.

Yak wool is a luxury fiber akin to cashmere and is still fairly rare so there are only a handful of companies using the fibers.

In addition to Oliver Charles, companies like Norhla make an array of yak goods.

Other products include knitting yarn, home goods, and even canvas.

Our post on yak and merino wool clothing looks at what the two fibers do when they are knit together.

Yak Wool FAQ

How Should I Wash It?

Oliver Charles All-Season Sweaters are machine washable. Our Winter Sweaters should be hand washed. We recommend reviewing the care label to make sure your sweater lasts forever.

Can I Knit With Yak Yarn?

Yes! You definitely knit with yak yarn. There are a plethora of companies selling it by the skien. A few of our favorites include: Myak, Ashland Bay, and ULA + LIA.

What Color Is Yak Wool?

Yak wool most commonly comes in a range of brown color. You can check out its natural beauty in our undyed product. There is some white yak fiber, but these yak are extremely rare. The white yak fiber is some of the most expensive in the world.

Would I Get Along With A Yak?

Almost definitely! Yaks have been described as the dogs of the bovine family. They have big personalities and love humans.

Is Yak Wool Warmer Than Sheep’s Wool?

Yes. Yak wool is around 40% warmer than sheep’s wool at the same weight, which is why a yak sweater can be lighter than a sheep’s wool one and still hold its heat. The reason is structural rather than magical. Khullu fibers are hollow and heavily crimped, so they trap more still air per gram, and still air is what insulates.

Is Yak Wool Machine Washable?

Yes and no. If you follow our guide to caring for wool, you can learn how to machine wash your wool sweater without shrinking or felting it. As far as wool goes, yak wool is well suited for machine washing, and without the plastic coating that makes most washable wool washable.

Wool fiber can be bent back on itself more than 20,000 times before it breaks, against about 3,000 for cotton, so it survives a machine cycle on its own strength (American Wool). Superwash treatments achieve the same result by coating the fiber in resin. Khullu does not need one, which is also why it stays biodegradable.

How Is Khullu Collected?

Yaks naturally shed their winter down every spring, and their herders comb the loose fiber from the animals or hand collect it as it sheds. Yaks are healthier when their wool is combed out in the spring. It helps them cool down going into summer.

How Much Fiber Does One Yak Produce?

One yak produces three to five times more usable fiber a year than a cashmere goat. That adds up. Fewer animals are needed for the same amount of clothing, which means less grazing pressure on the same grassland.

Warmth without the bulk. Oliver Charles knits khullu, the fine yak down.

Shop Yak Wool