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Best Ultralight Sleeping Bags 2021

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This is a review of the Best Ultralight Sleeping Bags for backpacking in 2021. There are so many choices of great lightweight sleeping bags on the market so I’ve narrowed the field down to the 5 Best Sleeping Bags.

All these were chosen for their quality, lightweight and small pack size. All the best ultralight sleeping bags in this review will last you many years and make a good investment. If you are looking for an even lighter option than take a look at the Best Ultralight Backpacking Quilts.


Best Ultralight Sleeping Bags 2021

The Best Ultralight Sleeping Bags for 2021 are:


Best Ultralight Sleeping Bag – Overall

Rab Mythic 400 Review

Weight – 23oz (660grams)
Down – 900+ down
Fill Weight 14oz / 400g
EN Rated – Yes
Packsize – 6.5L
Pros:

> Ultra Lightweight
> EN rated
> High quality
Cons:
> Expensive
> Half zip is considered a negative by some people but I like it, thought you should know

At 23oz / 660g this yet another awesome high quality sleeping bag. Like the Marmot Phase 20 and the Sea to Summit Spark this bag is EN rated so rest assured that it will definitely keep you warm when the temperatures get cold.

This bag is rated to 20F / -7C and is stuffed with high quality 900+ down.

The zip is only half length so it cannot be completely unzipped. This option makes it unsuitable for warm summer nights but does a perfect job of reducing weight.

This bag would be perfect for thru hiking the Continental Divide Trail, the Himalaya, Andes or any non summer hiking where temperatures regularly hover near or below freezing.

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Feathered Friends Hummingbird UL 20 Review

Weight – 24oz (680grams)
Down – 950+ down
Fill Weight – 14oz / 397g
EN Rated – No
Packsize – 9L
Pros:

> Ultra Lightweight
> 950+ down
> High quality
Cons:
> Expensive
> Clumping issues after extended use

The Feathered Friends Hummingbird is one of the lightest sleeping bags rated at 20F (-7C). It weighs 24oz (680g) and is stuffed with the highest quality 950+ down which helps keep the weight down.

This is a mummy style bag is suited to someone who wants the lightest bag possible and is not prepared to compromise on quality. The Hummingbird is roomy enough for most people but Feathered Friends have larger models for those wanting more internal room.

Triple Crown Hiker Rob “Stone” Sweeney has used the Hummingbird on the Continental Divide Trail, Arizona Trail, Hayduke Trail, Finger Lakes Trail, Long Trail, Colorado Trail, John Muir Trail and The Grand Enchantment Trail. He likes the lightweight, small pack size, high build quality and has had no issues with the zippers or cords.

Despite washing the bag at the end of every hiking season it is starting to develop some clumping issues. After an amazing 5000+ miles / 8000km of use it is starting to develop cold spots. The down is getting pushed to the sides when he turn in it, leading to cold spots overnight. Follow his journey on Instagram: @HikingStone

If you want more room inside the bag, look at the wider Swallow or Swift sleeping bags. They have the same high quality materials with slightly larger internal dimension and weight.

Although this back is not EN Rated it has similar specs to the Marmot Phase 20 and RAB Mythic 400 which are both EN Rated. A great lightweight choice.

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Western Mountaineering Ultralite 20F Review

Weight – 29oz (820grams)
Down – 850+ down
Fill Weight – 16oz / 450g
EN Rated – No
Packsize – 9L
Pros:

> Lightweight
> High Quality
Cons:
> Expensive

Western Mountaineering make some of the best quality bags but that comes at a high cost. The 29oz (820grams) sleeping bag is the most expensive bag in this review. The reward for spending this much money is a sleeping bag that will last a very long time.

It is a mummy style bag with enough room for all but the widest of people. It uses 850+ down unlike some of the other manufacturers that use the highest rated 950+ down. The bag is rated to 20F (-7C) and Western Mountaineering has a large selection of bags rated at different temperatures.

This is one of the best quality sleeping bags money can buy right now.

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Marmot Phase 20 Review

Weight – 23oz (660grams)
Down – 850+ down
Fill Weight – Unknown
EN Rated – Yes
Packsize – 6.5L
Pros:

> Ultra Lightweight
> Small pack size
> EN tested
> Great price
Cons:
> Zipper Issues

At 23oz / 660g this is the equal lightest of all the sleeping bags reviewed but one of the highest quality.

The Marmot Phase is EN tested 20F / -7C rated sleeping bag, so rest assured it will keep you warm.

The mummy style of most ultralight sleeping bags can be constrictive for some people. It has similar internal specs to the Feathered Friends, Western Mountaineering and RAB sleeping bags.

This bag comes in at a bit cheaper than the other ultralight sleeping bags without compromising quality or materials. So for those wanting the best quality at a reasonable price, this is the best option. Like many sleeping bags, the zipper can get stuck from time to time.

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Sea To Summit Spark 4 Review

Weight – 31oz (880grams)
Down – 850+ down
Fill Weight 22oz / 620g
Packsize – 6.5L
EN Rated – Yes
Pros:

> Price
> Small pack size
> EN rated
> Large amount of down fill
Cons:
> Heavier than the others in the review

Updated several years ago in 2019 from Sea to Summit. With a weight of only 31oz / 880g this bag is not as light as some of the others but is still very high quality.

The bag is EN Rated to 18F / -9C so sleep easy in the knowledge that it will keep you warm in cold weather. With 22oz / 620g of down fill it has the highest amount of down fill of all the bags in this review.

This bag is the roomiest of all the sleeping bags in this review and has a full length zip, which adds to the overall weight of the bag. Add to this the very small pack size and it makes a great lightweight sleeping bag option.

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Buyers Guide

Here is all the information you will need to make an informed decision about Quality Ultralight Sleeping Bags

Why Upgrade your Sleeping Bag

Recent years have seen the weight and pack size of sleeping bags reduce and the quality rise. For anyone who still has a bulky, heavy or poor quality bag it is time to consider throwing down some money on an upgrade.

The sleeping bags listed in this sleeping bag review represent the best on the market at the moment. All the Best Sleeping Bags for thru hiking are under 2lb (900g). If you are planning to lighten your for a long distance thru hike such as the Pacific Crest TrailContinental Divide TrailAppalachian TrailTe Araroa Trail or any of the other great Best Hiking Trails in the World, then a lightweight sleep system is one of your first choices.


Down vs Synthetic Sleeping Bags

This review is only dealing with the best Lightweight Sleeping Bags that are filled with down. It would be unfair not to mention the other option which is synthetic filled bags.

They are heavier and don’t pack to the same compact size as down bags. But they still insulate when wet and are cheaper, therefore many people see their value.

As materials continue to develop their may come a time when synthetic bags are better than down. That point has not been reached yet.

That being said, if you want to save money or are heading to areas where getting your sleeping bag wet would be life threatening, consider a synthetic bag.


Sleeping Bag Temperature Rating

Most of these sleeping bags manufacturers have self determined the temperature ratings of their bags. As a result they are not always the best guide of what is a comfortable rating. The industry recognised EN 13573 ratings standard is a European quality standard for the sleeping bag industry.

It can be expensive for companies to obtain this rating, few lightweight Sleeping Bag companies seem to bother. I’ve used EN rated bags in the past and find them to be very accurate measure of temperature rating.

The fill weight, or amount of down fill inside the sleeping bag or quilt varies quite a bit between all the manufacturers.

This might not seem like much but it can make a difference to the insulation of the bag. It would be easy to claim that the width or style of the internal baffling could lead one manufacturer to have a competitive advantage over another, and that may be the case.

The way internal baffles are constructed also affect the temperature rating. In some bags the down can be moved within the internal baffles to where it is needed most. I find this feature very annoying.

I want to unzip my sleeping bag to regulate the temperature, not wake up in the middle of the night and try to shuffle down within the baffles.

The Lightweight Sleeping Bags in the review are rated at around 20F (-7C) which is a good functional 3 season temperature range that can be used in all but the coldest and warmest of weather.


Lightweight Sleeping Bag Pac Size and Stuff Sacks

Keeping a sleeping bag dry while hiking is critically important. Heavy rain, a leaking backpack or a fall when crossing a river can make for an uncomfortable nights sleep at best and a life threatening situation at worst.

For many years I have used a Thermarest fleece stuff sac. Since then I’ve taken a look at the Best Backpacking Pillows and prefer to use a Sea to Summit dry bag for my sleeping bag stuff sack.

Recent years have seen many ultralight hikers make the switch to Dyneema stuff sacks such as those from Hyperlite Mountain Gear. These super lightweight, strong and waterproof stuff sacks come in multiple sizes and shapes to fit any sleeping bag and a good investment to keep your down bag dry.


Lightweight Sleeping Bag Price

The best Lightweight Sleeping Bags can cost a lot of money but it is money well spent. It is not unusual to keep a quality sleeping bag for 10 year. I kept a quality winter sleeping bag for 20 years before I decided to sell it.

In most cases it is not only money well spent, but one of the best investments you can make. All of the bags listed will last 10 years or more and range in price from US$280-$580.


Warranty and Return Policy

Before purchasing a Lightweight Sleeping Bags be sure to check the return policy. Make sure you can return it if you ordered the wrong size.

If it is returned after being used it may incur a ‘Cleaning Fee’.

Anything purchased from REI offers the best consumer protection, closely followed by Amazon with a 30 return policy. In all cases buyer beware, make your choice wisely.

How to wash a Sleeping Bag

Once you have purchased one of the Lightweight Sleeping Bags listed above it is time to look after it.

There are several ways to wash a down sleeping bag. The best methods are to hand wash them in a bathtub or on a gentle wash cycle in a front loading washing machine. It is my preference to wash my bag in a front loading washing machine.

The first step is to purchase a detergent that is specific for washing down, such as Nikwax or Grangers. Be sure to take a my full information guide on how to wash down sleeping bags.


Conclusion

Which is the best Lightweight Sleeping Bags for thru hiking and Backpacking? Any of the ultralight sleeping bags listed in this review would make a great option for anyone wanting to lighten up the weight they carry.

The choice for the best Sleeping bag is much harder than years ago. The Feathered Friends HummingbirdWestern Mountaineering UltraliteMarmot Phase 20 , Rab Mystic 400 and Sea to Summit Spark 4 are almost identical in quality, weight and pack size. They are all a great choice and I would be happy to buy any of them. The only thing separating them is price and the buyers location.

Overall, I would choose the Rab Mystic 400, by the smallest of margins, as the best sleeping bag in 2021.

The sleeping bags must be used in conjunction with a high quality, lightweight sleeping mat. Read the complete review of the Best Lightweight Sleeping Mats for more information.

For those living in the Europe RAB might be the cheapest and most available.

For those in Australia and New Zealand you should buy through Snowys.com or Macpac.

Another one of the Best Hiking Gear Reviews from BikeHikeSafari.


Want to know all about the best gear on the market?

Best Lightweight Sleeping Bags and Quilts
Best Ultralight Sleeping Bags
Best Ultralight Sleeping Bags

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About the Author:
Brad is an Australian who has completed the hiking Triple Crown after he hiked the Pacific Crest Trail, Continental Divide Trail and Appalachian Trail. He has hiked on every continent (except Antarctica) and has cycled from Alaska to Ecuador. He is an expert on outdoor gear currently living in Sydney, Australia.

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