Explaining Different Types of Boot Insulation [Guide]

The winter months can be brutal on your feet. Insulated work boots protect your feet from the elements, but not all insulation is the same. What are the different types of boot insulation?

Most boots rely on one of the following types of insulation:

  • 3M Thinsulate™
  • Primaloft
  • Aerogel
  • Zylex
  • Wool

3M Thinsulate is by far the most common type of insulation used in work boots today. It is known for being very lightweight and non-bulky, while still being very capable of retaining heat.

The weight of insulation in work boots will also vary, and can range anywhere from around 200g to 2000g. The most common weight of insulation used in work boots is 400g.

For the continental US, 400g boots will often be the best option for most workers, but I must emphasize, there will be exceptions. You may need to adjust heavier or lighter based on several factors, especially climate.

Your activity level on the job also greatly impacts the weight of insulation you need. And of course, insulation isn’t the only part of a boot that can affect warmth. But in general, 400g is the most common type of insulated work boot you will find on the market today.

***Here’s my advice. If you want a quick understanding of what type of insulation may be best for your insulated work boots, then watch my short 45 second video posted below that quickly explains what you need to know. Also, please subscribe to my YouTube channel by clicking the button below. Thanks!

In this article let’s take a closer look at the types of insulation used in work boots, and how they may affect the comfort and performance of an insulated work boot.

Insulated Boots

Insulated boots are just like regular boots, except they contain materials meant to keep feet warm in various weather conditions. They achieve this through the usage of different types of insulation.

While the original insulated boots are those made using natural insulators, such as sheepskin or other warmth-promoting materials, the modern insulated boot is a little different.

The Different Types of Insulation 

3M Thinsulate

Thinsulate, made and trademarked by 3M, is very useful in boots and outdoor gear because it is extremely warm despite being non-bulky and lightweight. The microfibers trap in heat, but don’t take up a lot of space.

Work boots insulated with 3M Thinsulate have a thin layer of insulation around the interior of the boot. Don’t worry, this layer won’t feel bulky and the boot itself fits just like a normal work boot.

Here’s a look at my insulated work boots that use 3M Thinsulate:


3M Thinsulate is known for its durability, meaning this insulation won’t wear out quickly. It is also used to insulate other types of winter outdoor gear, like jackets and waders.

The full list of benefits includes:

  • Retains body heat: 3M Thinsulate™ traps heat, allowing for your feet to remain warm.
  • Flexible: The material can bend with ease, which guarantees comfortability and a free range of movement.
  • Lightweight – Won’t make the work boot extremely heavy.
  • Non-bulky – 3M Thinsulate is non-bulky and won’t choke your feet when you lace your boots.

How warm is 3M Thinsulate? Well, that is going to depend on the weight of insulation used in the work boot.

As we discussed earlier, the weight of insulation used in work boots ranges from 200g-2000g. Anything above 1000g is reserved for extreme environments. For work boots, the most common type of insulation weight is 400 grams, although 200 grams and 600 grams are also quite common.


A leading brand in synthetic insulation, Primaloft, is a type of insulation developed for the U.S. Army in the late 20th century. The material is an all-in-one exclusive, protecting the user against many weather-related dilemmas and much more.

  • Highly Water Resistant: Primaloft is highly water-resistant and is designed to keep the user dry during intense downpours.
  • Lightweight: Originally used in the Army, the lightweight material allows for easy storage.
  • Water Repellant: In addition to water resistance, the material also repels water.

Primaloft is probably the second most frequent type of boot insulation used today. Having worn both 3M Thinsulate and Primaloft, they’re very similar, but in my opinion the Primaloft felt a bit fluffier against my foot.

Overall though, both Primaloft and 3M Thinsulate are great options for boot insulation, and can help keep your feet warm in dangerous temperatures.


Aerogel insulation was made by NASA in the 1990’s to help insulated the feet of astronauts. Since then, Aerogel has made its way into mainstream footwear, including some types of work boots.

This type of insulation is not near as common as 3M Thinsulate. It is used, at times, in combination with other types of boot insulation, like Primaloft.

  • Bi-Directional Technology: Aerogel is created with a technology that can keep your feet warm in the cold or cool in the heat. It provides both benefits regardless of location.
  • Flexible: This type of insulation is very flexible and won’t make boots feel stiff.
  • Lightweight: The material is “light as air,” providing next-level comfort.

Aerogel, being patented by NASA, is an advanced technology. Many people actually consider Aerogel to be the most lightweight, flexible, and affective insulation on Earth.

So, why isn’t it more common in work boots? Well, the rarity of the material drives up cost, and can put these types of boots in a price range above what most consumers want to spend.

Perhaps the most noteworthy quality of Aerogel insulation is its bi-directional technology, which means not only does it help keep your feet warm in the cold, it also helps keep your feet cool in the heat.


Some types of insulation are better for bitter cold, and Zylex would be one of them. Made up of multiple layers of insulation, Zylex is a common material used in boots made for dangerous climates.

The material was created by Kamik, a designer who creates boots that can withstand freezing temperatures and intense outside activity. Benefits include:

  • Multiple Levels of Warmth: Zylex comes with three to four levels of material that is of varying thicknesses.
  • Removable Liners: The liners can be removed and replaced. Therefore, if you need to clean the liner, you can do so easily. 
  • Weatherproof Capabilities: Zylex insulation is weatherproof. They have a reputation for withstanding freezing rain, snow, and sub-zero temperatures. 

For most climates in the continental US, this type of insulation may be overkill. If you are working in the high country, you may need to consider this type of insulation.

The most notable benefit of this insulation, besides warmth, is the liner itself can be removed, cleaned, or swapped, which is not the case for other types of insulation.


It is quite likely that you have heard of wool insulation, and the technique of using wool for insulation has been around throughout history. Throwing on your wool socks and wool boots may seem like a great idea, but not in every situation.

The main downside is wool is not weatherproof. It does have “water-resistant” properties, but it will not offer the same level of protection against the elements as the other types of insulation discussed.

Benefits of wool include:

  • Lightweight: Wool insulation is incredibly lightweight and can even be paired with other materials to further increase comfort.
  • Compressible Comfort: Due to the material, wool is easily manipulated and compressible.
  • Very Warm: Wool insulation can protect you against very cold temperatures.

Present day, there aren’t many types of work boots that use wool as the insulation. It is much more common to find a synthetic material, like 3M Thinsulate, used as insulation.

Different Levels of Boot Insulation

Boot insulation is measured in grams. As we discussed earlier in the article, work boots can range from around 200g to 2000g, but the most common range is 200g to 600g.

The higher the grams, the higher the intensity of the insulation. The most common weight of insulation used in work boots is 400 grams.

How Warm is Boot Insulation?

This will depend on the weight of insulation, and the type of insulation. And to complicate matters even more, most boot companies (for legal reasons) don’t assign a temperature rating to their boots.

I cannot guarantee warmth either. I don’t know your climate, activity level, personal comfort level, or even the type of insulation you are interested in.

But as I said earlier, 400g will be a good starting point for most continental US worker. Yes, there will be exceptions.

If you work in a more mild climate, 400g may be too warm, and 200g may be a better starting point. And you’ll also want to take into account how active your are on the job.

For more extreme climates, you will want something heavier than 400g. You can find work boots insulated up to 2000g, but as fair warning, your options become slim beyond 600g, and extremely slim beyond 1000g. To read more about options, visit our article linked below.

The main takeaway is if you’re looking for an actual temperature guarantee, for most companies those basically don’t exist, and we certainly can’t give one either.

Most companies won’t make themselves legally vulnerable by placing a temperature guarantee on a product. Unfortunately, as I have learned, sometimes it’s just trial and error to find the boot that best fits your winter needs.

What I wear

Ultimately, trial and error is the method I used to find a boot that works for me. In Kansas, I use both a 200g and a 400g work boot (insulated with 3M Thinsulate).

We get moderate winters here, and can have severe conditions. But we also do experience periods of mild winter temperatures.


So I personally rotate from 200g to 400g as the weather turns. I can’t make that a standard recommendation because I don’t know your job, climate, or personal comfort level, but that is what has worked for me.

Here’s a look at one of my 400g boots (Danner Quarry ~4 years old):


Pros and Cons of Insulated Boots


  • Warmth: Yes, insulated boots will help your feet survive the cold. They can help in ways that socks can’t, and are a nice thing to pair with a pair of warm work socks.
  • Comfortable: Synthetic insulations used in work boots (like 3M Thinsulate and Primaloft) are very lightweight and flexible and don’t damage the overall comfort of the boot.
  • Long-lasting: Insulation is designed for performance, and therefore lasts even in rough climates.


  • May cause your feet to sweat: If you plan on spending more time inside or in regulated temperatures, the insulation for your boots will likely cause your feet to sweat. They should be utilized in cold temperatures.
  • Expensive: Naturally, next-level protection such as this will cost you a bit more than normal boots.
  • Temperature Ratings: Most companies, for legal reasons, won’t assign a temperature rating to a boot, which means you are left to sort of guess which weight of insulation might be best for you.

Insulated Work Boot Options

If you are interested in using an insulated work boot, you can explore your options by clicking on our links posted below.

Again, 3M Thinsulate is by far the most common type of insulation used in work boots today. It is known for being very lightweight and non-bulky, while still being very capable of retaining heat.

Paul Johnson

Paul is a lead content creator for Workwear Command. He has had several blue-collar jobs which have provided him a wide range of experience with tools and gear. He also has a business degree and has spent time in business casual office settings.

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