If you plan to visit a cold part of the world this winter, you may want to stock up on clothes made from insulating fabrics. What type of socks will keep your toes the most warm, and what kind of material should you look for in a warm coat? To answer these questions, you need to learn about the warmest fabrics for clothes.
The warmest natural fabric in the world is wool, though a wool-acrylic blend provides even more insulation. The composition of the fabric also impacts its insulation abilities, as polyester fleece provides much more insulation than knitted or woven polyester. For sportswear, fabrics containing a high percentage of spandex will provide good insulation.
In this article, you will learn about the 15 warmest fabrics in the world. You will discover what material is best for a winter coat. Finally, you will find tips on how to avoid the worst fabric for cold weather.
15 Warmest Fabrics
The warmest fabrics you can wear include natural materials like wool and hemp, but they also include blended fabrics like wool-acrylic.
One way to determine how well a type of fabric will keep you warm is to check its thermal conductivity at a temperature of 59 ℉, which tells you how well a type of material can retain the heat from your body instead of allowing it to bleed off into the air around you. Material with a low thermal conductivity will keep you the warmest because they allow very little heat to escape.
Other fabric types, like silk, provide incredible warmth, but only when you wear them correctly in a layered technique.
Finally, the warmth of a type of fabric also depends on its construction. For example, polyester fleece provides incredible insulation, but plain-woven polyester does not.
1. Wool-Acrylic BlendOne of the warmest clothing materials you can wear is a blend of natural wool and synthetic acrylic. This mix costs less than pure wool because synthetic acrylic has a much lower price tag.
It also provides more insulation, with a thermal conductivity measurement of just 0.035!
This means that wearing a sweater or jacket made with a wool-acrylic blend will keep you warm because hardly any thermal energy will escape outside the cloth.
2. WoolWool is the warmest natural fabric, though exactly how well it retains heat does depend on the type of wool you select. For example, regular sheep’s wool has a thermal conductivity of 0.039, which is pretty great. But specialty wool, such as Icelandic wool, can have a thermal conductivity as low as 0.016!
The main reason wool has such great insulating properties is because of the natural shape of the fibers in this material.
Wool fibers have a twisty, kinked shape that traps tiny pockets of hot air against your skin, keeping you toasty warm.
3. AcrylicAcrylic fabric is a synthetic material made from a type of plastic. It is sometimes considered “poor man’s wool” because off-the-rack clothing often uses acrylic instead of more expensive wool. You probably have acrylic sweaters, coats, hats, and gloves in your closet without even knowing it!
The main reason acrylic keeps you warm is that it offers little breathability. This means that air does not move through the fabric and cannot carry away the heat trapped between you and the fabric. Because of this, you can also easily overheat in acrylic garments.
Though acrylic is one of the warmer synthetic fabrics, on its own, it only has a thermal conductivity of 0.054. This means it does not insulate you as well as pure wool.
4. CashmereLike Icelandic wool, cashmere can have as much as three times better insulation than regular wool. Cashmere has fine, slender fibers that contain a hollow air pocket inside. This traps millions of invisible air pockets within a garment, keeping you warm.
Why don’t more people wear cashmere clothing if it works much better than regular wool? Because cashmere is a rare and luxurious type of cloth that not everyone can afford.
Cashmere comes from a special type of goat called a Kashmir goat. Traditionally, true cashmere only comes from goats raised in the Gobi desert, but today people raise these goats in several parts of the world because cashmere is such a luxury fabric.
5. Merino WoolMerino wool is another specialty type of wool that provides extra insulation. White is not as insulating as cashmere with its hollow fibers, but merino wool does keep you warmer than regular wool because it has extra-fine fibers that trap more tiny bits of air inside its twisted coils.
Merino wool comes from a special type of sheep called, unsurprisingly, Merino sheep. The big difference between merino and regular wool is that merino wool has thinner, softer fibers. This makes it more expensive than regular wool, but it remains a popular choice for cold-weather apparel like sweaters and socks.
6. PolyesterPolyester is a synthetic fabric made out of a type of plastic, and on its own, it has a pretty good low thermal conductivity of just 0.048. As you may recall, regular wool has a much lower thermal conductivity of 0.036, so you can see that polyester does not keep you as warm as wool.
But this depends totally on the construction of the fabric. Polyester makes up over 60% of all ready-wear clothing sold worldwide today because it is cheap and easy to work with. This means that fabric manufacturers use polyester to form many different types of cloth, ranging from velvet to satin to fleece.
Depending on how the threads in the fabric weave together, polyester will offer greater or lesser insulation. Thin material like plain weave or jersey knit polyester typically provides little warmth.
But types of polyester woven or brushed with a raised surface that creates many tiny raised fibers on the fabric’s surface will trap a ton of heat and keep you extremely warm. This includes types of cloth like polyester flannel and–most noticeably–polyester fleece.
Another reason polyester can keep you warm because, like acrylic, it does not have great breathability. This means that not much air will get through it to carry away your body heat into the outside air.
7. Polyester FleeceOne of the warmest types of polyester fabric you can wear is polyester fleece. This material has a thermal conductivity 0.034, better even than pure wool!
Of course, this does vary a bit depending on the thickness of the fleece because you can find many different versions of poly-fleece for sale today. Some have a thick, soft nap and others feel thin and less insulating. It also depends on the tightness of the weave because closely packed polyester threads will keep you warmer than loosely woven polyester threads with gaps for air to escape.
Polyester fleece keeps you so warm because it has a pile, or layer of raised fibers, on both sides of the material. This is made by weaving many loops of thread together and then using a machine to cut down the loops, leaving millions of tiny cut fibers on the surface of the cloth. All of these tiny fibers trap air pockets, keeping you warm.
Polyester fleece also resists moisture, making it a good choice for outdoor apparel in cold weather.
8. MicrofleeceMicrofleece does not necessarily provide more insulation than regular polyester fleece, but it weighs a lot less, which makes it a better choice for activewear in some cases.
This type of fleece uses tiny threads, even finer than silk threads, to create the soft pile on both sides of the material that traps so much heat.
Microfleece also does a great job repelling moisture like raindrops or snow.
Microfleece is popular for base layers like thermal undergarments for cold-weather hiking or camping.
Silk has a high thermal conductivity of 0.066, which allows a lot of warmth to escape through its fibers into the outside air. But you will often find silk listed as one of the warmest fabrics in the world because it can provide incredible insulation–if you wear it properly.
Silk contains natural air pockets, which can trap air and regulate your body heat, keeping you warm and cool in cold weather. But the best way to use silk as an insulator is to wear it as a base layer, with other, bulkier clothing on top of it. This allows the air pockets in the thin silk to retain the heat from your body.
In fact, people have worn silk in layers like this for thousands of years as one of the best natural heat-retention methods out there!
10. Cotton-Acrylic Blend
Blended fabrics like cotton and acrylic mixed also make a popular choice for cold weather clothes because the acrylic fibers provide insulation and the cotton fibers provide softness and breathability.
On its own, cotton does not keep you very warm. It has a thermal conductivity of 0.040 at a temperature of 59 ℉, much higher than wool or acrylic in pure form. But if you blend cotton with one of those warmer fibers, you can create a comfortable, soft material that feels good on your skin and keeps you warm.
11. Viscose-Lycra Blend
A viscose-lycra blend is a popular choice for soft, stretchy sportswear like leggings or tank tops that can keep you warm in the winter under certain conditions. This material has a high and ineffective thermal conductivity measurement of 0.104, largely because viscose (a type of rayon) does not retain heat very well.
But in terms of synthetic sportswear, this measurement ranks pretty well. Lycra/Spandex/elastane fibers trap heat well because they have zero breathability. These stretchy fibers come from a type of rubber and give your sportswear that elastic stretch you need for high-action activities.
In practical terms, the percentage of Spandex or Lycra in the blend will determine how warm your sportswear feels in cold weather. A higher percentage will mean a warmer garment with lower heat conductivity.
12. Cotton-Polyester Blend
Clothing made from a blend of cotton and polyester also makes a popular choice in cold weather, though it does not keep you as warm as pure polyester, with a thermal conductivity rating of 0.120 at a temp of 59℉. However, the comfortable softness of cotton in the mix often makes an acceptable trade-off for people who want comfy winter clothes, not just warm ones!
Pure cotton has remarkable softness and great breathability. Unfortunately, its airy breathability makes it a poor choice for insulation. At a temperature of 59℉, 100% cotton has a thermal conductivity of 0.040. Of course, just as with 100% polyester, this does depend on the construction of the cloth.
For example, cotton fleece will provide much more warmth than denim, canvas, or pain-woven cotton.
The most insulating activewear or sportswear clothing you can find often contains a large percentage of Spandex. Spandex is a brand name for a type of elastic fiber made out of rubber. It also goes by Lycra (another brand name) or the unbranded name of elastane.
Spandex is not necessarily a warm fabric, but its fibers do not have pores, meaning that no air flows through it. This makes it warm simply because it traps all air and heat against your skin, especially if you wear form-fitting clothing such as a fitted tee or leggings.
Gore-Tex fabric is a brand-name material that provides windproof and waterproof outerwear in bad weather. While it does not necessarily have great insulating properties, it ranks highly for cold weather wear because it can protect you from the elements better than almost any other material. Keeping dry is an important part of staying warm in the winter!
Like silk, Gore-Tex does its job best when you wear it in layers. Adding thermal base layers that trap heat and a protective jacket or coat made out of Gore-Tex on top will keep you both toasty and dry for outdoor winter activities.
While it is a lesser-known fabric, hemp offers greater insulating properties than cotton and still provides breathability to keep you comfortable. This is because hemp fibers have many tiny cracks and crannies, giving them a porous nature.
Hemp offers a good alternative to wool or synthetics for a base layer in your outdoor ensemble. But it is often not used for outerwear like coats because it has such great breathability.
Best Material for Winter Coat
Wool, fleece, and either acrylic or an acrylic-wool blend often make the best choice for a warm winter coat.
Adding layers of stuffing, such as down inside a coat, can also add incredible warmth, as you will find in types of coats like puffer jackets. The fabric used as the shell of this kind of coat does not insulate at all, as it is usually a whisper-thin layer of nylon or silky polyester. But the layering of insulating material inside the shell forms a heat-trapping mechanism that works super well.
In terms of one fabric on its own that makes a thick, warm winter coat, go with either wool or acrylic. Polar fleece (a thick, plush form of polyester fleece) also makes wonderfully warm winter jackets or parkas.
What is the Warmest Material for:
Now that you know all about how well various types of fabrics provide insulation, take a look at which kind of cloth works best for particular garments like shirts and jackets.
A few of the warmest fabrics you can use for a shirt include polyester flannel shirts, thermal base layer shirts, or any shirt made of wool.
For everyday wear, shirts made out of polyester woven in a construction that traps heat will keep you warm. Flannel is popular because it has brushed, velvety fibers raised on the material’s surface, which helps keep you warm.
For hiking or active wear, you may consider finding a thermal base layer long-sleeved shirt. Popular choices for the fabric include wool, merino wool, or special synthetics.
If you need to dress up but want to stay warm, you can also find high-end shirts made out of finely woven wool.
The warmest material for a jacket can vary a lot, depending on the style of jacket you prefer. For example, a puffer or ski jacket gets warmth from the insulating filling sandwiched between the shell and the lining. The shell material does not keep you warm on its own.
On the other hand, you can also find wool jackets or fleece jackets that keep you warm simply because of the thick, heat-trapping ability of the fabric itself. In this instance, look for a wool, acrylic, or polyester fleece jacket.
The warmest and softest sweaters you can find contain luxury wool like cashmere. However, any wool sweater will provide great warmth, especially if you wear it over a thinner shirt to add a base layer to your outfit.
Other popular choices for warm sweaters include acrylic and polyester. Acrylic sweaters keep you warm but sometimes feel scratchier than wool sweaters. Polyester sweaters do not provide as much warmth as acrylic or wool, but they cost very little and keep you warm if you add a shirt beneath.
When you choose a dressy sweater, avoid fine cotton knit sweaters if you want to stay warm. Cotton sweaters feel airy and comfortable and can make a great choice in fluctuating temperatures in the fall when you don’t want to get overheated. But they will not keep you as warm in truly cold weather.
When you select the warmest material for pants to wear in the winter, you have to consider the thickness of the material rather than just the kind of fabric used. If you want a pair of dressy trousers to wear with a blazer, fine wool offers the warmest option. But a thick type of cotton trousers will also keep you quite warm.
If you don’t need to look dressy and plan to engage in hardy outdoor activities, you may want to wear thermal leggings or fleece-lined tights beneath a shell of weather-resistance fabric like Gore-Tex. Layering is the best way to keep your legs warm, just like it is for your torso!
The easiest way to pick the warmest blanket is to look for a thick blanket with a fleecy or velvety pile or surface. Thick, fuzzy blankets have tons of tiny fibers and pockets to trap your warmth against your skin. This is why polar fleece blankets and throws make such as popular choice.
The warmest material for winter socks is either wool or a wool-acrylic blend. You should not go with pure acrylic, as it will trap in too much heat and cause your feet to sweat.
Pure wool offers a great option for winter socks if you can afford it. Wool can provide moisture-wicking properties to keep your feet dry besides keeping your toes warm!
Fabric Warmth Chart
This fabric warmth chart will give you a quick overview of the most insulating types of cloth. Keep in mind that the construction of the cloth also plays a big role in determining how well it will keep you warm, though. For example, a thicker polar fleece will provide more warmth than a thinner version of polar fleece.
This means that this chart is a guideline at best, and any insulating material like wool can keep you warm in the winter!
|Fabric||Thermal Conductivity at 59℉||Best For|
|Specialty Wool (Icelandic or Cashmere)||0.016||Pricy but the warmest option for high-end sweaters|
|Polyester Fleece||0.034||Jackets, pullovers, and winter blankets or throws|
|Wool-Acrylic||0.035||Cheaper but efficient substitute for pure wool socks and sweaters|
|Wool||0.039||Best for high-end thermal base layers, socks, sweaters, and even blankets|
|Polyester||0.050||Used in every type of clothing, including winter activewear and coats|
|Acrylic||0.054||Sweaters and hats|
Materials That Retain Heat Longest
Wool retains heat longer than any natural fabric, while nylon retains heat better than most synthetic fibers.
On its own, nylon does not make a great choice for many types of warm clothing like sweaters. However, it offers an excellent and affordable substitute for silk and can serve as the perfect insulating base layer. You also see nylon used a lot for the outer shell on down-filled coats to trap in the hot air filling up all the tiny hollow spaces in the down feathers.
What Thick Fabric Keeps You Warm in Winter?
The best thick fabrics to keep you warm in winter include polyester fleece, thick wool knits or wovens, and wool-acrylic blends in knits like sweaters and hats.
Manufacturers measure the thickness of fleece in GSM or grams per square meter. Look for a GSM of over 300 or the term “heavyweight” to find the thickest, warmest fleece option for a coat or blanket.
What Material Absorbs the Most Heat?
Polyester absorbs the most heat of any common clothing material, and cotton absorbs the least. That said, other factors also impact this, such as the color of the cloth. Under a direct heat source like sunlight, black or dark-colored fabric often absorbs more heat than white fabric that reflects light away.
And, of course, as you know, the woven or knitted structure of the material and its thickness will impact how well that absorbed heat can keep you warm.
Is Cashmere Warmer Than Fleece?
Technically, cashmere has a lower thermal conductivity than fleece and is, therefore, a warmer fabric. But this depends on many factors, and fleece can keep you warmer outdoors more effectively than cashmere in some circumstances.
First, fleece dries much faster than cashmere. That means if you go out on a damp, chilly day, you will get warm faster in fleece than cashmere.
Second, you often find fleece in a much thicker weave than cashmere. This is because cashmere costs so much. Cashmere is often reserved for dressier items like fine sweaters or thin items like a base layer hiking shirt.
The super thick fleece used in a coat may keep you much warmer than a fine, elegant cashmere peacoat or jacket!
Worst Fabric for Cold Weather
Cotton is the worst commonly used clothing fabric for cold weather. Of course, you could argue that many less-often-used types of material, like gold lame or tulle, also don’t keep you warm!
But of the fabrics often used to make sweaters and other winter apparel, cotton does the worst job of keeping you warm. So, why is it used? Because cotton feels soft and cozy and makes you feel comfortable!
Just keep in mind that wool will offer a lot more warmth.
What is the Warmest Clothing Material?
Specialty types of wool like cashmere, Icelandic wool, or Merino wool are the warmest clothing materials you can choose for winter apparel, such as sweaters, socks, or coats. Wool-acrylic blends also offer a great deal of warmth. Clothing made out of 100% polyester or 100% acrylic can also provide great insulation, but this largely depends on the construction of the fabric.
Any fabric with a nap or pile on its surface will keep you warm because all the tiny raised fibers catch pockets of hot air and hold onto them. Likewise, thicker fabrics such as polyester fleece provide amazing warmth. Finally, some fine fabrics like silk also keep you warm, but only when worn in layers with other garments on top.
What is your favorite fabric to wear in the winter? Does it keep you warm all the time? Leave a comment below to let us know!