REI Magma 15-Degree Unisex Sleeping Bag Review

I tested the new unisex REI Magma Sleeping Bag on a 3-night backpacking trip and loved how warm and comfortable it was. Get the full details on this awesome sleeping bag in this review.

Close up of a woman's head inside of the hood of the REI Magma sleeping bag

If you have ever felt too cold in your sleeping bag while tent camping, then you know how miserable it is to spend the night shivering and counting down the minutes until sunrise. I previously used a 30-degree car camping sleeping bag for backpacking trips, but it was bulky, heavy, and provided no warmth whatsoever.

Since I didn’t have a quality sleeping bag designed for backpacking, it took up a ton of room in my pack and added unnecessary weight to my load. I had gotten used to putting on extra layers before hitting the hay, but even with these warm clothes, I would often wake up freezing throughout the night.

I recently tested the new REI Magma 15-degree Sleeping Bag on a backpacking trip to Havasu Falls as well as a Spring car camping trip in Colorado. At Havasu Falls in early March, the forecast predicted wind, rain, low temperatures in the 20s, and surprisingly, even a chance of snow. So I wanted to pack a sleeping bag to keep me warm in these conditions. Plus, since I had a 20-mile trek with my backpack, I wanted a sleeping bag that was light and compact.

This sleeping bag was a game-changer for me. It fit in my pack with room to spare, and I didn’t need the extra layers or hand warmers I brought for nighttime. I had some of the best nights of sleep I’ve ever experienced while tent camping. 

This review demonstrates how the new and improved REI Magma Sleeping Bag lives up to its name, keeping you as warm as magma even on chilly nights. In this REI Magma Sleeping Bag review, I share the pros and cons, details on the technical features, and my personal experience using the 15-degree version of this sleeping bag.

Sponsored by REI Co-op

REI Co-op is my favorite outdoor gear retailer and a long-time supporter of my work here at Bearfoot Theory. Their 1-year return policy for Members is hands-down the best industry, and Members also get 10% back on their purchases every year.

REI Magma Sleeping Bag Overview

Although the REI Magma Sleeping Bag is not brand new (Kristen, BFT’s Founder, hiked with an earlier version on the John Muir Trail), it has been recently updated in both 15-degree and 30-degree. It now comes in unisex versions that include more sizes and fit more body types. REI’s goal with the rerelease of the Magma Sleeping Bags is to help more people find sleeping bags that fit them properly so they can comfortably sleep in a tent while enjoying the outdoors.

Woman pulling the REI Magma sleeping bag out of its stuff sack
Pulling the sleeping bag out of its stuff sack to set up camp

Why is the perfect fit important? If a sleeping bag is too big or loose, you’ll feel cold. I’m 5’9″, which often puts me in between sizes for sleeping bags. Having to size up means I have too extra room at my feet resulting in my feet getting cold. It also means carry a bigger bag than I need, which adds more weight and wastes precious room in my backpack.

On the other hand, if your sleeping bag is too small, you won’t fit in the bag. Your shoulders might not be fully covered, and you won’t have room to move around properly.

Finally, not all women fit in what would be considered a women’s bag, and the same is true for men. This new unisex sizing structure is a huge improvement for getting a custom fit no matter your gender or size.

REI Magma 15-degree Sleeping Bag

Key Features

  • Best Use: Backpacking
  • Shape: Mummy
  • Fill: 850-fill-power goose-down
  • Gender: Unisex
  • Sizes: 9 (short, regular, and long with three different widths)
  • Weight: 2 lbs – 2 lbs 11.3 oz
  • Compressed volume: 6L – 9.4L
  • Price: $429

Where to shop

What I love

  • Inclusive sizing: You can choose the best size based on your height, shoulder girth, and hip girth.
  • Warmth: The 850-fill-power goose down keeps my body warm from head to toe.
  • Zipper: The zipper wraps around my chest for easy unzipping, and the internal anti-snag strip prevents the zipper from getting stuck on the fabric.
  • Hood: The hood contours to the shape of my head and cinches to keep my head warm.
  • Draft collar: The draft collar prevents heat from escaping around my neck.
  • Compression: The sleeping bag compresses tightly into a provided stuff sack for easy packability.
A hand pulling out the REI Magma sleeping bag from a backpack

What I don’t like

  • Cost: Like many quality sleeping bags, this is a long-term investment. If you’re on a budget, consider buying when it’s on sale. REI also offers discounts throughout the year to REI Co-op Members.
  • Small stash pocket: The interior stash pocket for personal items is small and doesn’t have a zipper to keep things from falling out. Depending on the size of your phone, it may not fit in the pocket. It is big enough for a headlamp however.
Close up shot of my phone inside of the interior stash pocket of the REI Magma sleeping bag
My iPhone 12 fits inside the interior stash pocket of the sleeping bag, but larger phones may not fit
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    I started backpacking several years ago, and although I have tried and owned several sleeping bags over the years, I have never owned one specifically designed for backpacking. There was so much initial backpacking gear to purchase for my new hobby that I overlooked the importance of investing in a quality sleeping bag.

    I figured I could wear lots of warm layers to bed and be comfortable. This was a mistake since I always woke up cold throughout the night, and my biggest regret is not getting a technical sleeping bag for backpacking sooner.

    I got the best nights of sleep I’ve ever had while tent camping in the REI Magma Sleeping Bag. I move around a lot in my sleep and change positions constantly, but the sleeping bag kept my body comfortable whether I slept on my back, side, or stomach.

    Woman sleeping on her side on a sleeping pad in the REI Magma sleeping bag
    Sleeping comfortably on my side in the sleeping bag

    The path of the zipper wraps around your chest so you can zip it while lying inside the sleeping bag. The zipper also features a cover to keep it from getting stuck on the fabric. This made for a smooth, quick zip, even when I was zipping it up using one hand.

    The Magma Sleeping Bag also feels super soft and plush. I found myself excited to bundle up in the sleeping bag as soon as it got dark outside, and I didn’t want to leave my sleeping bag in the mornings because of how cozy it felt.

    It’s comfortable for lounging while reading my book, drinking my morning camp coffee, and organizing my gear inside my tent. Plus, I like how I could easily grab my headlamp or phone from the inner stash pocket as I needed them while hanging out.

    Photo of a woman sitting outside her tent on a sleeping pad with the REI Magma sleeping bag


    Most sleeping bags come in one standard size for men and another for women. With the new REI Magma Sleeping Bag, this isn’t the case.

    REI has redesigned the Magma Sleeping Bag to be nongendered or unisex. The sleeping bag now includes nine different size options so you can pick the best size based on your sleeping preferences and body shape in terms of height, shoulder girth, and hip girth.

    There are combinations of three different lengths and widths to choose from. This ultimately allows the sleeping bag to fit more bodies comfortably and provide a night of better sleep for everyone.

    REI Magma Sleeping Bag Size Chart
    Size chart

    To find the right size, I recommend measuring yourself with a tape measure and using the provided size chart to ensure you get the best fit. I am 5’9” and have a standard build, and when I compared my measurements to the chart, I found that a medium would fit best.

    Woman laying down in the REI Magma sleeping bag on a sleeping pad inside of a tent
    I am 5’9″ and found the medium-sized Magma sleeping bag to fit perfectly

    The medium fits me true to size and contours to the shape of my body, and I have the perfect amount of extra width in the bottom of the bag to spread my feet apart in the foot box. I slept in this bag for three nights in various positions and never felt like it was too tight or restrictive, or that I didn’t have enough room to move my arms and legs.

    I have a standard one-person insulated backpacking sleeping pad and found that the sleeping bag fits perfectly on top of it in terms of length and width. I also used an inflatable pillow and attached it to my sleeping pad with a Pillow Strap underneath the hood and found the set-up quite comfortable.

    The hood of the REI Magma Sleeping Bag is contoured and has two different drawcords, allowing for easy adjustments throughout the night. Even inside the sleeping bag, I like how I can cinch the drawcords of the hood if I’m feeling cold. The hood also fits well around my head and doesn’t feel too loose or tight, and if I ever needed to add a beanie for extra warmth on a particularly chilly night, I’d have the room.

    A woman laying down in the REI Magma sleeping bag in a tent and smiling
    The bag has lots of adjustments around the hood depending on how cold you are

    The foot box of this sleeping bag allows space for your feet to move. The trapezoidal shape reduces excess space to keep you warmer and decreases the overall weight of the sleeping bag.

    The sleeping bag ranges in length from 65 inches to 77 inches, so if you are over 6’5”, it will likely be too short of a sleeping bag for you. It may also feel too long if you are significantly shorter than 5’4”. For this reason, I docked half a star for fit.

    If you are between measurements or sizes, you can choose to size up or down depending on how you prefer the sleeping bag to fit. Keep in mind that a sleeping bag that fits tighter to your body provides better insulation, while a looser fit offers more space inside.

    If you are a co-op member (I highly recommend becoming an REI member if you’re not already), you can also return or exchange the bag for another size within 365 days of purchase if the size you buy isn’t working.

    Close up shot of the REI logo on the Magma sleeping bag in a size medium
    With nine different unisex sizes to choose from, you can pick the fit that’s best for you


    I brought the 15-degree Magma sleeping bag on my trip. When I camped, the temperature fell below freezing into the upper 20’s, yet I stayed warm in my sleeping bag and never woke up feeling cold.

    The sleeping bag has 850-fill-power goose down, so it keeps me feeling warm at night but never too hot. The bag also features a draft collar, which comfortably fills the space between the neck and shoulder gap to keep heat from escaping. It is adjustable, so I can keep it where I need it.

    Close up shot of the draft collar on the REI Magma sleeping bag
    The draft collar helped keep heat from escaping my sleeping bag throughout the night

    When I went to bed at night, I wore a base layer, leggings, and wool socks. I did not need to wear my beanie, gloves, or extra pants like I needed to on previous backpacking trips.

    Because I was nervous about the nighttime temperatures, I also brought hand warmers and filled my Nalgene bottle with boiling water to put in the foot box of the sleeping bag to keep my feet warm at night. However, I didn’t need to use either of these because the sleeping bag kept me plenty warm and toasty all on its own.

    On one of the nights when the low temperature was around 40 degrees Fahrenheit, I unzipped the bag because I got a little too warm. As someone who tends to run cold when sleeping outside, this rarely happens to me, but I was able to easily unzip the bag while half asleep to regulate my temperature.

    A hand pulling the zipper on the REI Magma sleeping bag
    I like how I can easily unzip the sleeping bag as needed throughout the night

    The shell is bluesign-approved recycled ripstop nylon, meaning it has been manufactured to meet high safety and environmental requirements. It has a durable water-repellent (DWR) finish to prevent moisture from getting inside the bag. If any moisture or condensation were to get inside my tent, I like having the peace of mind that the shell would prevent the insulated part of the sleeping bag from getting wet.

    REI used an independent testing protocol (ISO) to establish the Magma Sleeping Bag’s Temperature Rating of 15 degrees Fahrenheit.

    The Comfort rating for which this bag will keep the average “cold sleeper” comfortable is 21 degrees Fahrenheit. I can attest that it did its job there! The Lower Limit rating is 9 degrees Fahrenheit – which is the lowest temperature at which the bag will keep the average “warm sleeper” comfortable.

    It’s important to note that sleeping bags made for women typically have more insulation (making them 10-15 degrees Fahrenheit warmer) than men’s sleeping bags since women tend to sleep colder than men. This means that on average, women may find the 15-degree sleeping bag suitable for temperatures slightly above 15 degrees, while men may be able to comfortably use it for temps that fall slightly below 15 degrees.

    Of course, your body temperature can run hot or cold regardless of gender. Consider all of this information when deciding between the 15-degree and 30-degree versions.

    Temperature range label printed on the inside of the REI Magma 15 degree sleeping bag
    The temperature range printed on the inside of the Magma 15-degree sleeping bag

    Weight and Packability

    The sleeping bag includes a stuff sack for packing on trips and a big mesh sack for breathable storage when you’re not using it at home.

    I found that the stuff sack compresses the sleeping bag extremely efficiently for packing. Believe it or not, this 15-degree sleeping bag compresses down smaller than many popular 30-degree sleeping bags designed for backpacking. 

    The compressed volume ranges from 6 liters to 9.4 liters, with my medium-sized bag at 8 liters. I packed the sleeping bag into the bottom compartment of my 45-liter backpack and noticed I had room to spare, making it easy to quickly stuff the bag in and take it out of my pack. If you pair it with a compression sack, you can get the packed size down even smaller.

    A woman pulling the REI Magma sleeping bag out of a backpack
    The sleeping bag fits well in the bottom of my pack, even without a compression sack

    Depending on the size you order, the weight of the 15-degree sleeping bag ranges from 2 lbs to 2 lbs 11.3 oz. My medium-sized sleeping bag weighs 2 lbs 3.6 oz which is fairly light for a 15-degree sleeping bag. 

    To compare, the regular-sized women’s NEMO Riff 15 Endless Down Sleeping Bag weighs 3 lbs 4 oz, a little over a pound more than my medium REI Magma bag. On the other hand, the regular-sized unisex Sea to Summit Spark 15 Sleeping Bag only weighs 1 lb 9.7 oz, though it costs over a hundred dollars more at $549.

    The long version of the REI Magma sleeping bag weighs in at 2 lbs 8.5 oz. Although this is comparable to the weight of other long sleeping bags for some brands, it is heavier than others. For example, the long version of the unisex Sea to Summit Spark 15 bag is 1 lb 11.7 oz.

    Size comparison of the REI Magma sleeping bag in its stuff sack next to a Nalgene water bottle
    A size comparison of the REI Magma 15-degree size medium sleeping bag to a Nalgene water bottle


    The REI Magma Sleeping Bag is made durably to last for years of backcountry adventures. Although the sleeping bag material is super soft, it’s tear and snag-resistant.

    I appreciate how along the entire length of the zipper, the bag has a strip of fabric designed to prevent the zipper from snagging on the sleeping bag material.

    I have always struggled with sleeping bag zippers getting caught on the fabric when adjusting the zipper at night and worried about it tearing or forming holes. It is a relief to no longer have to deal with this annoyance.

    Woman setting up the REI Magma sleeping bag inside of a tent
    The material of the sleeping bag is soft yet durable

    To keep the sleeping bag at its best for years of use, I recommend hand washing it as needed. If you must use a washing machine, wash it only on a warm, gentle cycle in a front-load washing machine. Use a gentle, detergent-free cleaner like Nikwax Down Wash Direct designed for washing down products. 

    To dry, do not wring the sleeping bag. Either air dry or tumble dry in a machine on low. To prevent damaging the delicate material, do not use bleach or an iron. 

    Once your sleeping bag is clean and dry, store the bag loosely in the provided mesh sack instead of the compression sack. These cleaning practices will help to extend the life of your sleep bag.

    The REI Magma sleeping bag inside of a tent with green grass and rocks behind it
    Caring for your sleeping bag properly will allow you to enjoy it on adventures for years to come

    Where to Buy

    The REI Magma Sleeping Bag is available at REI stores and online, and you can purchase either the 15-degree or 30-degree version. Both of these come in nine different sizes so you can order the best fit for your body. If you prefer a quilt instead of a sleeping bag, check out the Magma 30 Down Trail Quilt

    Frequently Asked Questions

    Should I get the 15 or 30-degree Magma sleeping bag?

    While the 30-degree bag is slightly lighter and more compact, it’s not as versatile as the 15-degree version. You should think about where and what seasons you plan to use the sleeping bag. If you will be high up in the mountains, I’d recommend the 15-degree bag. It’s worth the few extra ounces to ensure your warmth. However, if you plan to use it only in summer in hotter climates, than the 30-degree bag should suffice.

    How much does the Magma sleeping bag cost?

    The 15-degree version is $429. The 3-degree version is slightly cheaper at $379.

    Is this sleeping bag waterproof?

    No, it is not fully waterproof. The lining has a water-resistant coating, but the bag will not stay dry if it’s submerged in water (ie if water is pooling up inside your tent or if you fall while crossing a river with your backpack on)

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    Do you have questions about this REI Magma Sleeping Bag review? If you own this bag, what is your favorite part about it? Let me know in the comments below!

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