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Emily Pennington | 10.26.2018

REI Joule 21 Women's Sleeping Bag specs

  • Weight:
    • Regular (up to 5 feet 6 inches): 2 lbs 3 oz
    • Long (up to 6 feet): 2 lbs, 5 oz
  • 700-fill hydrophobic duck down fill
  • Temperature Rating: 21 degrees (F) comfort (9 degrees (F) lower limit)
  • Materials: 20D nylon taffeta (lining), 20D ripstop nylon (outer shell)
  • Stuff Sack: 8 x 18 inches
  • Mummy shape

Where to get it

  • Price: $300-$320
  • REI

The Bottom Line: The Joule 21 is a great three-season bag made out of the same, 20D nylon ripstop and taffeta that comprise many similar bags from big-name outdoor retailers. Coming in at just over 2 pounds, it's a lightweight alternative to bulkier bags, making it the optimal choice for those who want to cut back on weight and go ultralight. Plus, the deep, wine color it comes in is absolutely stunning in person.

The REI Joule 21. Photo by Emily Pennington.

The Joule 21 initially struck me as incredibly similar to The North Face's Women's Blue Kazoo, which comes in right at the same price point but is rated for 15 degrees Fahrenheit and only weighs one ounce more. Though both are made with the same 20D nylon ripstop on the outside and 20D nylon taffeta for the inner lining, the hand-feel of The North Face's bag felt a bit softer, particularly across the outer shell. One reason for this might be the durable, water-repellent finish that REI coated their ripstop with, making this sleeping bag ready for wetter, more humid climates.

The REI Joule 21 comes with all the standard features that you'd want in a lightweight backpacking bag without too many bells and whistles that can add unnecessary weight. One feature I loved was its incredibly cozy neck puff that is shaped better than any other I've seen on the market. It protrudes out a bit from the bag itself and has a wrap-around "U" shape to make you feel tucked in and ready for some Zs. The fact that it's almost scarf-like in shape is important to note, as many similar bags only have an extra puff of down around the neck area, and REI's design is intended to keep heat in more effectively than the rest.

For those extra chilly evenings, there's also a drawstring to cinch the face area of the sleeping bag tightly around your head for maximum heat retention. This does, however, make it difficult to sleep in any position other than on your back, so keep that in mind if you're a stomach or side sleeper (like me) who will be pushing the bag down to its lower levels. 

It's worth noting that this sleeping bag has regular and wide options in its sizing, which is an optimal choice if you like to sleep in different positions or hate having a bag that constricts your feet and legs in the night. It does weigh a bit more, though, coming in at 2 pounds 10 ounces for a sleeping bag that fits a human up to 5 foot 6 inches.

The Joule 21 is filled with 18 ounces of 700-fill power hydrophobic duck down, which is great if you want to stay warm, dry, and still save on weight. This down, paired with its water-resistant outer fabric layer, makes the Joule an ideal bag for hikers living in wetter climates like the Pacific Northwest. Sadly, I live in Southern California, so I was unable to test it in a rainstorm, but other online reviewers seem to really dig it for staying dry!

Other key features include double zippers to vent heat near the footbox, if desired, or to unzip all the way and combine with a compatible sleeping bag for a two-person cuddle fest. Good news - REI sleeping bags are designed to be compatible with one another!

At the end of the day, this is a great sleeping bag that is similarly priced with other 15 to 20 degree bags on the market. While it isn't the cheapest 21-degree bag out there, it definitely earns a solid consideration due to its cozy neck warmer and its commitment to high-quality, water resistant materials that will keep you dry in the middle of a summer downpour in the Cascades or the Rockies. If you live somewhere dry or mostly camp in desert climates, it's worth getting a warmer bag for about the same weight and price and looking at The North Face's Blue Kazoo. But, at just over 2 pounds for the regular or the long, REI's Joule 21 is a hearty, ultralight three-season bag that packs down small and won't ruin a good night's sleep in wetter weather.


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