Therm-a-Rest  Boost 650 20F/-6C Sleeping Bag

$299.95 – to $374.95

Find your ideal balance of space and warmth. With a customizable shape, the Therm-a-Rest Boost 650 20F/-6C sleeping bag transforms from a roomy semirectangular bag to a thermally efficient mummy bag.

Color: Blue
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Location Image for Boost 650 20F/-6C Sleeping BagLocation Image for Boost 650 20F/-6C Sleeping BagLocation Image for Boost 650 20F/-6C Sleeping Bag
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Features

  • The Boost 650 was built to backpack—with dialed-in materials and design to make it light, packable and high-performing in variable backcountry conditions
  • As a spacious semirectangular sleeping bag, the Boost 650 provides all the room you need to side sleep, shift about, spread out and relax
  • Zipping up the WarmZip center zipper transforms the shape of the Boost 650 from a semirectangular bag to a thermally efficient mummy bag
  • WarmZip pulls the 650-fill-power down around your body and reduces the amount of space your body needs to heat, adding up to 10F (6C) to the Boost 650's temperature rating
  • Shell and liner are made of GRS-certified 100% recycled nylon that was handpicked for its light weight and supersoft feel
  • 650-fill-power RDS-certified hydrophobic down is allocated to key areas with Zoned Insulation for refined heat efficiency and maximum coziness
  • Zoned Insulation places the down in key warmth-retention areas (on top, around your core and shoulders) and reduces it where it's less efficient (on the bottom)
  • PFAS-free durable water repellent (DWR) coating and hydrophobic down keep the Boost warm and comfy even in wet weather
  • Armholes let you reach the WarmZip, read a book, play cards or simply ventilate—do it all while tucked into your sleeping bag for elevated livability
  • 2-way side zipper lets you ventilate around your torso or down by your feet
  • Every zipper line on the Boost 650 has a durable YKK antisnag pull to eliminate annoying snags and damaging tears
  • Standard Therm-a-Rest features like a puffy draft collar, a draft tube along the entry zipper line, and a cinchable hood round out the Boost 650's bliss-inducing comfort
  • Inclusive sizing lets you get the bag you want in the fit you need
  • Comes with compression sack and a storage sack

Imported.

Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.

Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
View all Therm-a-Rest Backpacking Sleeping Bags

Technical Specs

Best Use

Backpacking

Tested Lower Limit

20 degrees (F) - ISO

Tested Comfort

32 degrees (F) - ISO

Temperature Rating (F)

20 degrees (F)

Temperature Rating (C)

-6 degrees (C)

Weight

Short: 2 lbs. 4 oz.

Short Wide: 2 lbs. 13 oz.

Regular: 2 lbs. 11 oz.

Regular Wide: 3 lbs. 5 oz.

Long: 3 lbs. 1 oz.

Long Wide: 3 lbs. 13 oz.

Shell

20-denier 100% recycled nylon ripstop

Zipper Location

Left

Insulation Type

Down

Water-Resistant Down

Yes

Fill

650-fill-power duck PFAS-free hydrophobic down (RDS)

Fill Weight

Short: 1 lb. 4 oz.

Short Wide: 1 lb. 11 oz.

Regular: 1 lb. 7 oz.

Regular Wide: 2 lbs.

Long: 1 lb. 10 oz.

Long Wide: 2 lbs. 4 oz.

Sleeping Capacity

1-person

Lining

20-denier 100% recycled nylon ripstop

Sleeping Bag Shape

Semirectangular

Fits Up To (in.)

Short: 66 inches

Short Wide: 66 inches

Regular: 72 inches

Regular Wide: 72 inches

Long: 78 inches

Long Wide: 78 inches

Shoulder Girth (in.)

Short: 63 inches

Short Wide: 75 inches

Regular: 64 inches

Regular Wide: 76 inches

Long: 65 inches

Long Wide: 77 inches

Hip Girth (in.)

Short: 59 inches

Short Wide: 73 inches

Regular: 60 inches

Regular Wide: 74 inches

Long: 61 inches

Long Wide: 75 inches

Stuff Sack Size

Short: 18 x 6.5 inches

Short Wide: 18 x 6.5 inches

Regular: 20 x 7.5 inches

Regular Wide: 20 x 7.5 inches

Long: 20 x 7.5 inches

Long Wide: 20 x 7.5 inches

Stuff Sack Volume

Short: 9.8 liters

Short Wide: 9.8 liters

Regular: 14.5 liters

Regular Wide: 14.5 liters

Long: 14.5 liters

Long Wide: 14.5 liters

Compressed Volume

Short: 7.1 liters

Short Wide: 7.6 liters

Regular: 8.7 liters

Regular Wide: 9.4 liters

Long: 10.9 liters

Long Wide: 10.1 liters

Gender

Unisex

Sustainability

Down certified to the Responsible Down Standard (RDS)

Contains recycled materials

Reviews
10 reviews with an average rating of 4.4 out of 5 stars

Ratings Snapshot

Product Rating

5 out of 6 (83%) reviewers recommend this product

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Average Customer Ratings

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy

Customer Images

Lala
Anchorage, AK
Rated 5.0 out of 5 stars

Spacious but cozy and warm.

4 months ago

After trying out several bags for backpacking, aI finally got this one and am really happy with it. I went with the regular wide. I’m a plus size gal and I tend to toss and turn when I sleep, so every mummy bag I tried just felt way too claustrophobic. This is nice and spacious, even when it is zipped up to the mummy version. Of course with all that spaciousness, the bag takes up a bit more space when packed, but to be able to get a good night sleep makes it well worth it for me. I also love the little zippers at the front so you can be in the bag but have your arms out. Nice little touch so you can read while staying nice and cozy.

Age:35–44
Weight:250–275 lbs.
Height:5'7"
Yes , I recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
MDF
Rated 5.0 out of 5 stars

Great sleeping bag

9 months ago

If you want a roomy, packable, down sleeping bag this is it. I don’t like mummy bags, I’m a big guy, they don’t work for me. I’ve had a lot of different bags over time but this one is by far the best. Vents and zippers move smoothly to find your comfort zone for both snug if you want, or vented and comfortable. Haven’t had it out in cold weather, but I’m confident the way it’s packed with down it will be fine down under 30 degrees. I spend about 30 nights a year around the country in tents, and have a closet full of pads/bags, and gear. This is my new go to bag for sure.

Age:45–54
Weight:225–250 lbs.
Height:5'10"
Yes , I recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
Lillian
Madison, WI
Rated 2.0 out of 5 stars

i am so so so cold

3 months ago

The first time I took this bag out camping it was 30°F and I woke up multiple times through the night absolutely freezing (wearing heavy wool base layers and socks) so I decided to wait till it warmed up a little more because I am a pretty cold sleeper and wanted to give it a fair chance. So I took it out camping when the coldest was going to be 36°F and I still woke up cold multiple times. I like this bag, I like it's versatility with all the zippers and vents, but the fact that it can't keep me warm at 36°F when it's rated for much colder than that is a huge turn off. I will be returning this bag.

Age:18–24
Weight:125–150 lbs.
Height:5'3"
No, I do not recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
Greenie
Sonoma Valley CA
Rated 5.0 out of 5 stars

Like it a lot!

1 month ago

I've only used this bag for 3 nights during a New Zealand hut trek in November so limited experience but so far I love it. In the hut I'd guess the temp was in the 40's (with approx. 30 bodies) b/c outside it snowed. I wore wool base layers to bed and was comfortable the whole time. I appreciate the venting for arms (didn't use much) and the flexbility to unzip lower part for more leg room (more comfortable for sideslipping and didn't need the extra coziness). Down Feels plush, not noisy fabric and beautiful aqua color. At 5'3" and slim I really appreciate the various size/weight options so I got the short; yay for not carrying extra unnecessary weight! The only thing I didn't love is that the head area wasn't big enough for my head resting on a small blow up backpack pillow. If it were really cold, I'd want my head inside the bag but in this case, it wasn't needed.

Weight:100–125 lbs.
Height:5'3"
Yes , I recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
Robert A.
Rated 5.0 out of 5 stars

I loooove this bag. It

2 weeks ago

I loooove this bag. It is lightweight, comfortable, and super warm. I honestly feel like I would've been fine with a 30 degree bag because I mostly camp in the summer, but the big vent in the front and the arm holes make a big difference as far as cooling me off. Also. . . . . . the arm holes are super sweet. They make it so you can read a book or look at your phone before you go to bed. I've had a synthetic bag for years, and the feel and construction of this bag fell amazing. I don't backpack often anymore, but this bag is plenty light and comes with a compression sack to get it nice and small for packing. Would definitely recommend. Again, I love this bag.

Originally posted on a Cascade Designs brand site
delicatessen
New York
Rated 5.0 out of 5 stars

In Love!

3 months ago

Wow! I'm out of words. I've never been more excited to receive a piece of gear. The first time I unboxed The Boost I knew I'm getting more than just a sleeping bag, I'm getting a new friend. The customizable design is simply mind blowing. This is my first sleeping bag and I'm coming for Boost after returning a quilt from a different company. Quilt offered lots of weight savings but turned out to be a pain to use - it needed to be attached to the sleeping pad, it had an open back and no hood?! I'm going on my first backpacking trip with 30s F at night and I need sleeping system that will 1000% keep me warm. Quilt I picked just couldn't offer that and I can't take any chances. With The Boost I see exactly where every dollar went - every detail is high quality and thought through. It leaves me at peace that I will be warm at night and it will serve for years to come.

Age:25–34
Weight:100–125 lbs.
Height:5'4"
Yes , I recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
SpookyHike
Rated 5.0 out of 5 stars

The BEST

3 months ago

I bought this last month for a 3 night trip in GA. This bag is definitely my new go to. It's warm, comfortable, and the arm holes are elite. I'm a super warm sleeper and the arm holes served as great vents. I may or may not be using it to stay cozy now that I'm home. Excellent purchase.

Age:35–44
Weight:150–175 lbs.
Height:5'3"
Yes , I recommend this product

Ease of Use

Difficult to useVery easy to use

Product Weight

LightweightHeavy
Helpful?
Jonathan W.
Rated 5.0 out of 5 stars

Great Bag!!

2 weeks ago

This bag is FANTASTIC for anyone who feels restricted in regular-width bags (or side-sleepers, or those who "flail about"). The fabric is super-comfy against the skin and yet, seems durable. Looking forward to many years of use!!

Originally posted on a Cascade Designs brand site
Colson S.
Rated 5.0 out of 5 stars

I recently spent 5 days

1 month ago

I recently spent 5 days camping out, this bag was great , very comfortable to sleep in, warm and roomy for a side sleeper. I recommend it often at REI.

Originally posted on a Cascade Designs brand site
Anonymous
Rated 2.0 out of 5 stars
1 month ago
Helpful?

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