How to Choose Sleeping Bags for Backpacking
REI Co-op Zephyr 25 Sleeping Bag
$199.95
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The REI Co-op Zephyr 25 is our top REI Co-op brand synthetic sleeping bag, ideal for backpacking from spring through fall. A new extended range of sizes delivers your best fit for better sleep.
Key Details
Fill
100% recycled PET polyester
Weight
Short Narrow: 2 lbs. 9 oz.
Short: 2 lbs. 12 oz.
Medium: 3 lbs.
Medium Wide: 3 lbs. 3 oz.
Long Narrow: 3 lbs. 2 oz.
Long: 3 lbs. 4 oz.
Long Wide: 3 lbs. 8 oz.
Compressed Volume
Short Narrow: 6.8 liters
Short: 7.3 liters
Medium: 8.3 liters
Medium Wide: 8.7 liters
Long Narrow: 8.8 liters
Long: 8.9 liters
Long Wide: 10.3 liters
Temperature Rating (F)
25 degrees (F)
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- Inclusive sizing lets you find your best fit based on body shape and sleeping preferences
- Semifitted mummy shape provides the roomiest fit of our backpacking bags, offering extra room in the knee area to enable a variety of sleeping positions
- Recycled shell and lining fabrics feature a nonfluorinated durable water repellent (DWR) finish to help moisture bead up on the surface
- 100% recycled synthetic polyester insulation is durable and highly compressible; the fill also retains some insulating ability even if it gets damp
- Shingle construction on top provides uniform loft and helps prevent insulation from shifting and creating cold spots
- Offset quilt construction on the bottom optimizes bag/pad system warmth while reducing unnecessary weight and bulk
- Comfortable hood shape works well for all sleep positions and allows for easy integration with a backpacking pillow (not included)
- 2 differentiated drawcords make the hood easy to adjust while you're zipped in the bag
- Insulated muffler and full-length zipper draft tube keep warmth in and cold out
- Zipper path wraps around the front of your chest so you can more easily zip and unzip the bag; zipper cover and internal antisnag strip allow for frustration-free zipping
- Roomy trapezoidal footbox provides space to move your feet while still remaining warm and cozy
- Keep personal items close and easy to access in the interior stash pocket
- Includes a stuff sack for packing and a roomy mesh sack for breathable storage
- Hand-wash or machine wash warm, gentle cycle in front-load washer only; do not bleach; rinse thoroughly; do not wring; air dry or tumble dry low; do not iron or dry clean
- Contains materials that meet the bluesign® criteria
- REI Co-op brand is certified to The Climate Label; we actively fund efforts to reduce carbon emissions across our business and support climate projects around the world
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. Our backpacking bags are rated for temperature according to an independent testing protocol: International Organization for Standardization (ISO) 23537. 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. For REI Co-op brand nongendered sleeping bags, we provide an overall temperature rating that falls between the Comfort and Lower Limit ratings.
View the REI Co-op Zephyr Product LineView all REI Co-op Backpacking Sleeping BagsEach 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. For REI Co-op brand nongendered sleeping bags, we provide an overall temperature rating that falls between the Comfort and Lower Limit ratings.
| Best Use | Backpacking |
|---|---|
| Tested Lower Limit | 17 degrees (F) - ISO |
| Tested Comfort | 28 degrees (F) - ISO |
| Temperature Rating (F) | 25 degrees (F) |
| Temperature Rating (C) | -4 degrees (C) |
| Weight | Short Narrow: 2 lbs. 9 oz. Short: 2 lbs. 12 oz. Medium: 3 lbs. Medium Wide: 3 lbs. 3 oz. Long Narrow: 3 lbs. 2 oz. Long: 3 lbs. 4 oz. Long Wide: 3 lbs. 8 oz. |
| Shell | 100% recycled ripstop nylon (bluesign approved) |
| Zipper Location | Left |
| Insulation Type | Synthetic |
| Fill | 100% recycled PET polyester |
| Fill Weight | Short Narrow: 1 lb. 13.8 oz. Short: 2 lbs. 0.4 oz. Medium: 2 lbs. 3.5 oz. Medium Wide: 2 lbs. 5.4 oz. Long Narrow: 2 lbs. 5.5 oz. Long: 2 lbs. 6.7 oz. Long Wide: 2 lbs. 9.8 oz. |
| Sleeping Capacity | 1-person |
| Lining | 100% recycled nylon (bluesign approved) |
| Sleeping Bag Shape | Mummy |
| Fits Up To (in.) | Short Narrow: 65 inches Short: 65 inches Medium: 71 inches Medium Wide: 71 inches Long Narrow: 77 inches Long: 77 inches Long Wide: 77 inches |
| Shoulder Girth (in.) | Short Narrow: 58 inches Short: 65.5 inches Medium: 66.5 inches Medium Wide: 74 inches Long Narrow: 60 inches Long: 67.5 inches Long Wide: 75 inches |
| Hip Girth (in.) | Short Narrow: 48.5 inches Short: 56 inches Medium: 57 inches Medium Wide: 65.5 inches Long Narrow: 50.5 inches Long: 58 inches Long Wide: 66.5 inches |
| Stuff Sack Size | Short Narrow: 7.75 x 12.5 inches Short: 7.75 x 12.5 inches Medium: 7.75 x 12.5 inches Medium Wide: 7.75 x 12.5 inches Long Narrow: 7.75 x 12.5 inches Long: 7.75 x 12.5 inches Long Wide: 8.25 x 14.5 inches |
| Stuff Sack Volume | Short Narrow: 10 liters Short: 10 liters Medium: 10 liters Medium Wide: 10 liters Long Narrow: 10 liters Long: 10 liters Long Wide: 12.5 liters |
| Compressed Volume | Short Narrow: 6.8 liters Short: 7.3 liters Medium: 8.3 liters Medium Wide: 8.7 liters Long Narrow: 8.8 liters Long: 8.9 liters Long Wide: 10.3 liters |
| Gender | Unisex |
| Sustainability | Contains materials that meet the bluesign® criteria Contains recycled materials From a Climate Label Certified brand |
Hip Girth The circumference at the widest point of your hips. | |||
|---|---|---|---|
| 39-45 | 32-39 | 45-52 | |
| Height | |||
| 4'11'-5'5'' | Short | Short Narrow | Short Wide |
| 5'5''-5'11'' | Medium | Medium Narrow | Medium Wide |
| 5'11''-6'5'' | Long | Long Narrow | Long Wide |
Sizing Notes
Measurements are stated in inches unless otherwise indicated. For Hip measurement, measure around your body at the widest point of your hip. If right at the edge of the measurements listed, size up or down based on your upper body size or how you prefer your sleeping bag to fit. A closer fit will provide better insulation, and a looser fit will allow for a bit more room. It’s important to not have too much room for proper insulation.
Buying Advice
Better gear is built together
From feedback to field testing, all of our gear is dialed-in by REI Co-op members. Their adventures informed every stitch and detail—making for better, longer-lasting gear.
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Customer Images
Smooth
Received free product
Ashgabat, Turkmenistan
Warm and cozy with huge zipper
7 months ago
I received these products for free from the REI Trailblazers sampling program in exchange for my honest review. I tested the sleeping bag down to 33° wearing one layer of clothing. I had no issues with cold throughout the night, very cozy. Overall it is a very nice sleeping bag. The zipper is huge and nice to operate and doesn’t get fabric stuck very easily. There is also a nice apron that keeps the hot air around your body when the opening for breathing is adjusted. My kids liked it so much that when they joined me in the morning they both crawled in together and fell asleep because of how cozy it was.
Age:35–44
Weight:175–200 lbs.
Height:5'8"
Yes , I recommend this product
Jessie
Received free product
Tahoe, CA
Great size, roomy and warm.
7 months ago
Used twice in 40*F degree weather. I am 5'4 and close to 200 lbs and my husband is 6' and close to 180 lbs. We both took a turn sleeping in it and it was comfortable for both of us - long enough for him without being too short. I put my outerwear in the bottom so I would have warm layers in the morning and the extra length in the bottom ended up being perfect. The width is really comfortable. Being larger I could lay on my back or either side without feeling too claustrophobic. It has a nice gusset inside by the neck area to help keep warmth in - the cinching for the hood was great. The zippers are high quality. I like that there is also a zip from the bottom option to get some air/ventilation if needed and made grabbing my layers in the morning easier. My husband stayed in the hood all night while I like to fold it down and use it more like a cushion. We both stayed warm and comfortable all night. I have a similar mummy bag in a different brand - they are comparable in a lot of ways but the extra length/width is the biggest selling point for me. Looking forward to using it again in colder weather!
Age:25–34
Weight:175–200 lbs.
Height:5'4"
Yes , I recommend this product
Jillian
Received free product
NW Montana
A lighter weight sleeping bag fit for a queen
7 months ago
This sleeping bag, while admittedly sent to me just after temps in my area plummeted to below 25 degrees, showed up as a bright spot on a grey day. Appearance wise, the colors are true to the photos and the sunflower gold interior allows you to spot any electronics you might happen to keep inside the sleeping bag at night with ease (and the wider shoulder gives you room to actually house them inside at night). If you are someone who doesn't like loose floating gear inside, there is a nice pocket large enough to fit large phones plus a little (flap pocket so it doesn't add any weight). For a 25 degree weighted bag it keeps you amply warm for temps about 25 degrees. Below 25 degrees I used it to supplement another sleeping bag like a quilt which ended up keeping me snug as a bug. The truest test of all however, and my personal favorite, is the Dog Test. Does the dog claim it as her own anytime I lay it down? Yes. Does she happily snuggle into it anytime, anywhere? Yes. Is it small enough that I can sleep in it solo and stay warm while also being big enough to cover both of us spooning (in the name of dog space heaters)? Also yes. Did it stay squeaky clean by letting every bit of dirt she could possibly track onto it sluff off like water on a ducks back? Astoundingly yes. I tried to get photos of it with my 5'5'' frame inside of it for reference but...alas, the doggo beat me to it every time so photos of the pair will have to suffice. Sorry not sorry.
Age:25–34
Weight:125–150 lbs.
Height:5'5"
Yes , I recommend this product
DanE
Received free product
Portland, OR
Great bag!
8 months ago
Bag arrived quickly and looks great! Not exactly camping weather here in the great PNW, but tried product overnight in my garage on a cot. Mid 40’s temps. I had an extra blanket, but didn’t need it. Bag was great! Especially like zipper which looks very robust and I’ve had issues with these in the past. I’m 6’4”, 220 lbs. Tall bag is plenty, but wide size would be helpful. Otherwise, bag is great and I’m looking forward to more adventures….not in my garage….:)
Age:65–74
Weight:200–225 lbs.
Height:6'4"
Yes , I recommend this product
carol
Missouri
super cozy
1 year ago
Loved this on a trip in the ozarks. It only got down to low 60s but I wasn’t too hot. The hood kept my inflatable pillow snug and I could still put my arms under the pillow in the bag. I roll around a lot and was able to do that in this bag.
Yes , I recommend this product
Geohacket
Received free product
Great performance an comfortable
7 months ago
I was very pleased with the performance of the Zephyr 25 this last weekend up in the Angeles Forest. We were finally able to break loose and get up to Hoagees camp ground (now that the road is open) and we did a quick over nighter. I tried out a hamoc I got for my birthday and with a pad the bag and a tarp it turned out to be one of the best sleeps I ever had while camping. The temps got down to mid 30s and the Zephyr stayed warp up to the point I had to vent a couple of times. The material is plush and doesn't make a lot of noise when I move around. Plenty wide for side sleeping and doesn't have cold spots do to tenting of the insulation. This was great trip due to a good sleep and fun friends. Plus the bag was lighter than my other low temp bag I've had for three years.
No happy
Montana
Failed at 35F degrees
10 months ago
Sleeping bag failed at 35 degrees. Will be returning it. Cost me a day of my trip to find a new Sleeping bag. I will not recommend it.
Height:5'2"
No, I do not recommend this product