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Hands-on Gear Review

REI Co-op Joule 21 Review

Editors' Choice Award
Price:   $299 List | $299.00 at REI
Pros:  Lightweight, high quality materials, warm
Cons:  Uncomfortable fit, zipper fabric bulky and uncomfortable
Bottom line:  The Joule is a great lightweight, quality choice for all your backpacking adventures.
Editors' Rating:     
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Manufacturer:   REI

Our Verdict

This is the second highest scorer in our review and shares the Editors Choice Award with the Rab Neutrino 400. It's heavier than the Neutrino but also warmer and much less expensive. It kept us warm and cozy on cold, wet, and windy nights in the High Sierra. The 700 fill-power down insulation provides a good night's sleep in the backcountry, and we appreciated its low weight-to-warmth ratio. In the 2017 update, the dimensions of the bag are no longer exaggerated.

New Version - April 2017
The Joule 21 was recently redesigned and we love all the changes, see more details below.

To see how the Joule compares to the rest of the sleeping bags we tested check out our Best Women's Sleeping Bag Review.

RELATED REVIEW: The Best Women's Sleeping Bag Review

select up to 5 products
Score Product Price EN Comfort Rating (F) Women specific features Total Weight (oz)
Editors' Choice Award
27 More insulation per square inch, womens specific cut 28 oz
Editors' Choice Award
23 Increased room at hips, decreased room at shoulders, extra insulation in heat loss areas 35 oz
Top Pick Award
25 Women-specific mummy design 42 oz
21.6 Increased room at hips, decreased room at shoulders, extra insulation in heat loss areas 41 oz
15 Women-specific cut to maximize warmth without constriction, extra insulation in torso and foot areas 40 oz
Best Buy Award
25 Smaller cut 47 oz
15 (Not EN rated) 1oz more down fill 44 oz
22 Women's specific cut. More insulation than men's version. 48 oz
21 Women-specific cut to maximize warmth and minimize weight 55 oz
25 (Not EN Rated) Shorter cut 52 oz
20 (Not EN Rated) Smaller Cut. 47 oz

Our Analysis and Hands-on Test Results

Review by:
Jessica Haist
Review Editor

Last Updated:
August 12, 2016


The New Joule 21 vs. The Old Version

The new, completely redesigned, Joule 21 was released in 2017. The shell is now made of 20-denier ripstop nylon and the lining is 20-denier nylon taffeta. The temperature rating is slightly warmer at 21 degrees Fahrenheit (versus 23) and the weight is the same. The list price for the Regular size remains the same as the previous model and you can identify the new model by its stylish Vin Rouge color.

Check out the side-by-side comparison below, with the Joule 21 pictured on the left and the Joule shown on the right.

Here's a summary of the key differences between the Joule 21 and the previous version:
  • New Lining Material — The new version features 20-denier nylon taffeta, updated from the Ripstop nylon lining in the older model.
  • Updated Shell Material — The Nylon taffeta is replaced with 20-denier ripstop nylon.
  • Lower Temperature Rating — The temperature rating is a touch warmer at 21 degrees Fahrenheit (versus 23).
  • Fresh New Color — Along with new construction details, the redesigned model also got a color makeover, donning a wine colored hue.
  • Wider in the Legs — Now roomier below the waist.
  • Neck baffle — REI calls it a "face-muffler". Wraps around your neck to keep heat in. See photos below. We didn't like this is earlier versions and we are still on the fence if we like it in the update.
  • Now only one drawcord - perhaps because of the baggle above, there is now only one drawcord for the hood. The drawcord for the neck was removed.
  • Zipper liner removed — this was not needed. Good riddance. Saves weight.

Hands-On Review of the Joule

The Joule is a top performer in this review. Our testers really liked its weight to warmth ratio.

Performance Comparison


After the Sierra Designs Backcountry Bed 800 Women's, we think this contender is one of the warmest sleeping bags in this review, and is just a little warmer than the Mountain Hardwear Heratio that is rated to 15 degrees. We feel that its EN rating of 21F is dead on, and indeed, it kept us warm down to that temperature. The bag feels cozy, and the 700 fill down is very lofty. The Joule's shell material protected our testers from wind when they slept out under the stars on windy nights. REI has eliminated the strange neck baffle from the previous version and we're glad because it didn't add much in terms of warmth, and we prefer a traditional baffle that can be tightened around the neck for added warmth

We took comfort in the fact that the bag's shell material has a waterproof coating when we were in a torrential downpour in a floorless shelter. It kept us dry throughout the night despite a constant misting from water bouncing off of the ground and tarp. This could be a good option for someone who wants a down bag in a wet climate like the North Cascades.


The Joule weighs in at 2 lbs 3 oz, which is not super lightweight for a down sleeping bag but is the 2nd lightest women's bag we reviewed (the Rab Neutrino 400 - Women's is 4.6 ounces lighter). This is a pretty average weight for a down backpacking sleeping bag, but we think it could be lighter. This bag weighs 3 oz more than the previous one, probably because of the change in fill weight.


One big change in 2017 is the shape. REI abandoned the woman's hour-glass shape and made the leg area larger. This was an upgrade. The proportions are about as exaggerated as Barbie's. There is lots of space in the articulated foot box, but not enough leg room around the knees. Then there is ample, if not too much space in the shoulders. All this is to say that we could have done with less room in the shoulder area, but our legs were a little too squeezed together. We do love how warm this bag is, and we like the feel of the material, so we forgave it for a little leg discomfort.

Packed Size

The stuff sack that is included with the Joule is not a compression sack, but is made from lightweight materials. When we took it out in the backcountry, we used one of our own compression sacks instead, and it packs down quite small. We really like the compression sack that comes with the Rab Neutrino 400 - Women's. Check out our The Best Sleeping Bag Stuff Sack review to find a compression sack that works best for you.


REI has trimmed the fat in this department and we are in favor of the work they have done. They have gotten rid of the stash pocket entirely and added a light colored liner fabric so you can find your missing sock without difficulty. We really like the pink liner color; it is light, but won't show dirt as much as the Mountain Hardwear Laminina Z Flame. The zipper works well, contrary to reports we read about this bag and so we are wondering what's with the super burly zipper lining fabric? We think it may be a reaction to complaints of zipper catching on this bag, but unfortunately, it adds weight and bulk and our testers can feel it when they're sleeping; it bunches and creates a hard, uncomfortable lump.

Although the waterproof coating on this bag works well, it also add extra weight. We do appreciate the degree of mental comfort it gave us when using it in an exceptionally wet summer season in the Sierra. We watched water bead off the coating with relief more than once in our floorless shelter, but we wonder how long this coating will last without being re-treated.

Best Application

This is a great bag for backpacking and camping. We dragged it along with us on many backcountry adventures when we wanted the lightest bag.


The Joule is a great value for your money and we agree that it is worth it to invest in a quality down bag like this model. At $240-300, the Joule is at the same price point as the Marmot Angel Fire and the Mountain Hardwear Heratio and it weighs less. It is a less expensive and potentially more durable option to the Rab Neutrino, although it is seven ounces heavier.


The Joule is warm and relatively lightweight, with the newest version of this bag reduced to 700 fill. But it is available for a lower price and is now a great deal. If it weren't for the uncomfortable zipper lining fabric, the lower fill power, and the tight cut around the legs. this bag would be neck and neck with our Editor's Choice, the Rab Neutrino; we still think it would be a great choice for your backpacking adventures.

Other Versions

The REI Serrana is slightly lower quality down bag and lower priced than the Joule. REI Lyra 24 is a synthetic fill bag similar in dimensions to the Joule. The Igneo is the men's version of the Joule.
Jessica Haist

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Most recent review: August 12, 2016
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