Sleeping Bags on the AT: Down Vs Synthetic For Warmth

When you’re sleeping out in the cold night air, the last thing you want is to be shivering and uncomfortable.…

When you’re sleeping out in the cold night air, the last thing you want is to be shivering and uncomfortable. That’s why it’s important to choose the right type of sleeping bag for your Appalachian Trail hike.

Down bags are more compressible and lighter weight at the same temperature rating as synthetic models, but they frequently are more expensive. If you’re on a tight budget, or if you know that there is a high chance the bag will get wet, then a synthetic model might be a better choice for you.

In this blog post, we’ll discuss the pros and cons of down vs synthetic sleeping bags when you are on the Appalachian Trail so that you can make the best decision for your thru-hike!

What are the Big Differences Between Down and Synthetic Insulation

There are some large differences between down and synthetic insulation. Down is a natural material made from down feathers, while synthetics are man-made materials like polyester or nylon made in factories.

Down has long been considered the gold standard of sleeping bag insulation because it’s lighter weight than nearly all synthetics at an equivalent warmth level.

However down can become useless when wet, which is why synthetic insulation has become more popular in recent years and especially in places where moisture and humidity reign supreme.

It is important to note that down and synthetics each have their own strengths depending on use case scenarios. Neither is the right answer all alone in a vacuum, finding and pairing the right one for your trip is where the real key to success lies.

Purpose of Insulation in a Sleeping Bag

Your insulation many think is to keep you warm, but this is mostly correct the misunderstood part is that the sleeping bag insulation’s purpose is to keep you warm from loss of heat to the air that surrounds you.

The insulation below you on the ground is essentially useless, this is why you want a high-quality sleeping pad as this helps to make sure you are insulated from the ground.

You can have a, for example, zero-degree rated sleeping bag, and be cold far above this rating due to losses in body heat directly to the ground below you.

The opposite side is the same, a zero-degree rated bag and an R-Value pad equal to this on the ground and you will sleep warm and toasty.

So always understand the sleeping bag insulation is to the air surrounding you and choose that based on the thru-hike temperatures you plan to encounter and pair it with an appropriate sleeping pad.

Benefits Of Sleeping Bag Insulation Choice

There are some good benefits to choosing down or synthetic which can change your experience on the trail.

Down as most know is an animal-sourced product where synthetic is a man-made material and non-allergenic.

Down Sleeping Bag Insulation Benefits

Down is amazing as an insulator, it provides an amazing amount of warmth to the weight required to carry it. Alongside this when properly cared for down has a decades-long lifespan and can be compressed incredibly.

Lightweight and Highly Compressible

One of the key factors to a long-distance hiker is having as small and lightweight a backpack as possible and the sleeping bag is one of those items where it is possible to drop pounds at first while still getting the same or better performance.

Down is very lightweight, which allows it to weigh less on your body over the 2100+ miles of the Appalachian Trail while simultaneously being very packable meaning inside the backpack it can take up less space.

These two factors combined to allow a thru-hiker to carry on with less wear and tear on their body, which all adds up over the miles you will hike.

Long Lifespan With Proper Care

Down is amazingly resilient and can give you excellent gear performance for over a decade as long as you provide them the care and management they require, especially if you thru-hike for months on end.

Down will get all the dirt and grime from a thru-hike slowly working into the fabric which means it has less loft over time and this means worse performance for heat retention, you can mitigate some of this on a long trail with the use of a sleeping bag liner as you can wash that in town easily.

For down washing, you need special detergent and to take care in the wash, no agitator so front load only, then no heat dry and some tennis balls to help break up large clumps and allow the down to distribute around again.

Amazing Warmth to Weight Ratio

The king stat for down is in the weight-to-warmth value it provides, there isn’t anything in the synthetic sleeping bags that can rival the low weight but high warmth that down provides to a sleeper.

This can be used to find the perfect blend of weight, for example using higher fill power down like 700FP to 900FP will be a huge saving in ounces of weight while providing the same warmth.

Synthetic Sleeping Bag Insulation Benefits

There are loads of benefits to choosing a synthetic sleeping bag also for an Appalachian Trail thru-hike.

Synthetics maintain their warmth even when wet, they dry very quickly, and have no animal parts in use so they tend to be the best allergy-friendly option.

Warm Even When Wet

Synthetic insulation is amazing when wet or when you can’t get dry due to consistent moisture over days and days of hiking and setting up.

This ensures that even on the worst of weeks you have a warm place to go rest at the end of the day, even if still slightly damp.

Dries Out Quick

A huge benefit to synthetic fiber use for insulation is that is also able to dry out very quickly with any level of airing out and sunshine, this is in contrast to natural fibers which typically can take a long time to dry well and normally need down to be re-distributed over time with wetting.

This is perfect for thru-hikers as it means you can trust and believe in the performance of your sleeping bag and know you are ready for another long week on the trail with a warm place to sleep at night.


Synthetic insulation is perfect for those that have allergies to down, as there is no animal down in the insulation material.

This means you don’t have to worry if you are going to have a reaction while on the trail and can rest assured knowing your sleep system will not cause issues.

Animal Cruelty-Free

Since it doesn’t use animal-sourced down feathers, it is also a more cruelty-free choice for those who are looking to make sure they haven’t caused harm to animals in the creation of their gear.

Less Expensive

A huge benefit to those with a set amount or budget that all their gear needs to fall into, synthetic is immensely less expensive than a similar down sleeping bag making it ideal for those who need to approach with money as a primary factor.

Drawbacks To Sleeping Bag Insulation Choice

With benefits come drawbacks, there is always a yin and yang to nearly any product that is created, for example, down is poor performing when wet or gets overly dirty and not cleaned well and synthetic has a significantly shorter lifespan and is bulkier.

Down Sleeping Bag Insulation Drawbacks

Down has a tremendous amount of upside to it but while there are solid good points to the use of down there are many issues that can be perceived as weaknesses or drawbacks to the use of this material in sleeping bags.


Down is not cheap, this means that down is going to be heavier on the pocketbook, down sleeping bags can reach prices around twice the cost of a similar synthetic bag that has similar temperature ratings.

For those facing a budget crunch, the down sleeping bag is probably not going to be the best option.

Gear Failure When Wet

One main issue for all down gear is its total failure if it gets wet or significantly damp, down relies on its loft to provide that warmth retention, and once wet the down basically deflates.

This means making sure above all that you keep down as dry as humanly possible at the front and center of any hiking trip, let alone a thru-hike where you will be outside for a week or more at a time.

Synthetic Sleeping Bag Insulation Drawbacks

There are some issues you may have if you choose to purchase a synthetic sleeping bag vs a down sleeping bag.

Down is less compressible meaning you may need more backpack space internally and it doesn’t perform to the same warmth levels without weighing more in general.

Doesn’t Compress Like Down

When you are looking at a synthetic sleeping bag you will find they don’t compress significantly as much as a down version of the same warmth rating, this means you need to focus on a larger pack size to accommodate the space consumed by the bag itself.

You will get a lot of use out of a compression sack if you go with the synthetic as it can help add some more overall compression to make the sleeping bag the smallest size possible.

Poor Weight-to-Warmth Ratio

Another shortfall of a synthetic material versus the down material is in the warmth to weight of the gear itself, synthetic is a bit heavier for the same warmth ratings, while down is downlighter and warmer.

If you have to choose between down or synthetic this is something that may influence your decision in which way you go but it shouldn’t be the primary deciding factor unless weight saving is extremely important to your hike.

Shorter Lifespan

Synthetic fabric breaks down over time the folding and crushing slowly break down the synthetic fibers causing them to have a significantly lessened lifespan.

Unfortunately, the insulation just doesn’t last as long and the entire bag will need to be replaced down the road if you want a sleeping bag that is maintaining its warmth properly.

What Role Does the Appalachian Trail Play in This Choice?

Now, since we understand both the bag insulations from the above sections you can now make an informed decision with an understanding of how the choice will impact your Appalachian Trail thru-hike.

There are really two main points which both have to do with the levels of moisture that can occur and that you need to understand they exist though in full transparency I use a down sleeping quilt and wouldn’t prefer a synthetic as I keep it in a stuff sack inside a liner inside my pack.

Constant Rainfall

The AT is known for consistent rain during all seasons you will plan to hike, summer won’t remove rainfall from the schedule, so if you are planning to hike using a down sleeping bag you need to have multiple failure levels set so that your sleeping bag isn’t impacted by a leak.

Most will choose a “waterproof” backpack but these are still prone to seepage over time as nothing is “fully” waterproof, so you may want to look into a backpack liner to be inside the pack protecting the important dry gear.

In addition, adding a waterproof stuff sack can add another additional level where you would need multiple failures to have a serious issue.

High Humidity

The other issue is that outside of the rain, there is loads of humidity so much of the time what is wet will stay wet, your chance to dry things will come with finding gaps in the trees to get direct sunlight and where possible place high in areas where wind can help to dissipate the moisture.

Final Thoughts on Down Vs. Synthetic Sleeping Bag Insulation for the AT

When it comes down to it, the choice between down and synthetic sleeping bags for the Appalachian Trail can be a difficult one. There are pros and cons to both options, but ultimately it depends on your own personal needs and preferences.

If you are looking for a high-quality down sleeping bag then the Classic or new Zpacks Zip Around Sleeping Bag is probably one of the most solid options available.

If you are feeling wild, I suggest a quilt and you can’t go wrong with the UGQ Bandit, you get to customize the ever-living daylights out of it to make it perfect for you!

If you’re worried about moisture or humidity levels on the trail, down may not be the best option. However, if you’re willing to take some precautions against water damage, down is a great choice because of its superior warmth-to-weight ratio.

If you want to see my favorites for all gear take a look over the gear section as I build out useful lists.

Josh Koop

I turned 40 and realized I needed to change my life from being a desk-bound IT worker slowly dying in a cubicle. I have been working on ways to build my knowledge and skills, along with gear. I have plans to do a thru-hike on the Lone Star Hiking Trail, Ouachita Trail, and Pinhoti Trail in the next year.

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