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REI Co-op Radiant 20 Sleeping Bag Review

David Wilkinson author bio photo 1_1
ByDavid Wilkinson
May 06, 2026
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Our Take:
4.4/5
Certified

The REI Co-op Radiant 20 stands out as one of the better values in backpacking sleeping bags, offering legitimate three-season warmth and a surprisingly high-quality feel for just $209. I tested it on spring backpacking trips and found it consistently cozy, with a soft liner fabric, roomy-but-not-too-roomy fit, and thoughtful features like a draft collar, snag-free zipper pull, and synthetic insulation in the footbox. It’s undeniably heavy and bulky compared to premium down bags, but that’s the tradeoff for the approachable price. For beginner and intermediate backpackers—or anyone who values comfort and warmth over shaving ounces—the Radiant 20 hits a sweet spot without many of the usual budget-bag compromises.

Warmth / Weight

Warmth / Weight

3.5/5
Comfort

Comfort

4/5
Features

Features

4/5
Durability

Durability

3.5/5
Water Resistance

Water Resistance

2/5
Sustainability

Sustainability

4.9/5

Temp Rating

25/13˚F (ISO Comfort/Limit)

Weight

2 lb. 11 oz.

Fill

1 lb. 9.4 oz. of 600-fill down

Shell

Polyester

Shoulder/Hip Girth

66.5/57 in.

Packed Volume

10L (6.7L compressed)

Other Temps

N/A

Pros

A great price for a well-built sleeping bag with this level of warmth.
Lining and shell fabric have a noticeably soft feel.
Thoughtful features, including a draft collar and tube, and synthetic insulation in the footbox.
The zipper has smooth action, which is not a given at the budget end of the sleeping bag spectrum.

Cons

Heavy at 2 pounds 11 ounces, taking it out of the running for fast and light trips.
The 600-fill-power down is not as lofty as more premium bags.

For this season's top models, see our guide to the Best Backpacking Sleeping Bags.

With backpacking sleeping bags, the warmth-to-weight ratio can be a pretty scientific calculation. The REI Co-op Radiant 20 has an ISO Comfort Rating of 25 degrees Fahrenheit (Lower Limit of 15, so REI splits the difference in naming it the Radiant 20), and weighs 2 pounds 11 ounces. This puts it above a bag like the Nemo Disco 15, which has a Comfort Rating of 27 degrees and is 2 pounds 14 ounces, though it has a more generous hourglass shape. The Kelty Cosmic 20 is a misnomer with a Comfort Rating of 31 degrees Fahrenheit—even its Lower Limit of 21 is above the “20” in its name. That bag weighs 2 pounds 7 ounces, so 4 ounces less than the Radiant, although considerably chillier, and we found it to run colder than even its listing ratings.

Realistically, the REI Co-op Radiant 20 is a heavy sleeping bag, and its warmth-to-weight ratio can’t come close to that of pricier high-end sleeping bags. You can get nearly identical temperature ratings in a premium option like the Western Mountaineering Ultralite, not to mention a smaller packed size, at 1 pound 13 ounces (14 oz. less than the Radiant). But that bag costs a whopping $660—three times the Radiant—and is aimed at a different type of backpacker altogether. Instead, the REI is best suited for moderate to short backpacking trips when weight and space are not at a premium.

Last but not least, the Radiant packs into a 10-liter stuff sack and can be compressed to a slightly smaller package. This is fairly par for the course for a 20-degree backpacking sleeping bag, although true minimalist designs like the Sea to Summit Spark get all the way down to 6.8 liters. The additional liters will be noticeable for those with smaller-capacity packs, but the differences in packed size are not quite as dramatic as in weight.

The REI Co-op Radiant punches above its weight in terms of comfort. Whereas competing budget bags like the Kelty Cosmic 20 have a cheaper-feeling shell fabric and lower-quality down fill that doesn’t offer the same loft or packability, the Radiant is downright cozy. The 20-denier recycled polyester is soft against the skin and has a quality feel. The shoulders are relatively roomy at 66.5 inches (the Cosmic is more constricting at 62 in.), which then tapers to 57 inches at the hips. It’s true that premium 800-fill-power (and higher) down results in bags that are even more pillow-like. But overall, I slept extremely well in the Radiant.

In terms of shape, the Radiant is a middle-of-the-road mummy bag (REI labels it as “semifitted”). Side sleepers and those who really toss and turn at night should consider a roomier bag like the Nemo Disco 15, which has similar warmth at the same weight, but is quite a bit pricier at $300. Personally, I don’t love highly constricting sleeping bags, but I find that a normal-fitting one is good enough for me. The Radiant feels just right in terms of comfort and space to move.

The REI Co-op Radiant 20 offers a nice feature set given its low price. The bag has synthetic insulation in the footbox, which comes in handy if you happen to brush your feet against condensation at the end of the tent (either from your breathing or from a little exterior moisture making its way in). It also has a healthy draft tube, collar, and “face muffler” (interesting name) to cinch up the area around your face for extra warmth. Importantly, I liked the smooth zipper, which has a cover and internal anti-snag strip that did its job (I experienced no snags even when zipping haphazardly with one hand). Inside the bag is a small pocket for small items like a phone or headlamp. All in all, a budget price tag, but nice features.

Denier is the measure of fabric thickness, and the REI Radiant has a 20-denier recycled polyester shell fabric, which is fairly durable for this product category. For comparison, the Nemo Riff is also 20D, while REI’s own Magma is a moderately thinner 15D. You can go thicker with a sleeping bag like The Mountain Hardwear Bishop Pass, with its 30D shell, but the Radiant feels sufficient in this regard. And I’ll be honest: Unless I'm bringing my dog along, I don’t care much for a thick sleeping bag shell fabric. The bag is either in storage or in a stuff sack inside my pack. Inside the tent, there is very little chance of tearing it (I’ve never punctured a sleeping bag in my life aside from accidentally snipping one when cutting off the tag). With a dog, denier might matter. Otherwise, I pay little mind.

The overall build quality of the bag is another key factor in its durability, and the Radiant 20 seems well-made. As mentioned previously, the zippers have a quality feel and smooth action (zippers can be some of the first things to do, and aren’t always easily repaired), the shell fabric is supple and soft next to the skin, the stitching is all in place, and none of the other small components feel cheap (even the stuff sack has a quality feel, although we’ll likely replace it with a compression sack). Last but not least, I’ve had good experiences with REI sleeping bags and pads in general over the years. The build quality of REI’s in-house products punches above their price.

The vast majority of backpacking sleeping bags are filled with down (synthetic insulation is too heavy and bulky for the backcountry), and they are not designed to get wet. Consider swapping in a waterproof compression sack for peace of mind, or make sure it stays dry inside your pack (if you don’t have a premium pack made with Dyneema or Aluula, or a pack cover, a trash bag liner is rudimentary but works).

Aside from those measures, the REI Co-op Radiant 20 has a DWR finish that will help light moisture bead off rather than soak in. The down is not treated with any sort of water-repellent finish—REI does treat the down in its high-end Magma, which is a nice touch but not a major selling point for me. Just keep your bag dry, full stop.

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Longevity

Choosing durable outdoor gear and keeping it in use for longer is one of the best ways to reduce environmental impact. Our proprietary longevity rating assesses factors like overall build quality, materials, fabric denier, component durability, and real-world performance. A green check indicates that we expect the product to be long-lasting relative to its peers, a yellow check mark indicates average longevity, and a red X indicates a product that may have a limited lifespan.

The REI Co-op Radiant 20 in a medium fits backpackers up to 71 inches, which was a real test, given that I am exactly 71 inches tall. The bag did the job, although—as expected—with no room to spare. Luckily, REI offers the bag in a whopping nine size options. You can choose from “Short” (65 in.), “Medium” (71 in.), and “Long (77 in.), and all three come in “Narrow,” regular (no extra moniker), and “Wide” versions. The specs are too many to list individually, but all are available on the product listing page and should give you ample options to choose from. If you are very tall (above 6’5”), the Radiant might not work for you, but there are options elsewhere. Western Mountaineering makes its Alpinlite all the way up to 7 feet in length!

Kelty Cosmic Down 20 ($190): Bargain Basement
Sleeping bag manufacturers seem to name their bags however they please, as in, it doesn’t necessarily match the Comfort or Lower Limit ratings—and some aren’t rated at all. Looking at the name, the Kelty Cosmic 20 seems to be in the same category as the REI Radiant, at a slightly lower weight and price point, but the data says otherwise. The Kelty has a 31-degree Comfort Rating and 21-degree Lower Limit (the REI is 25 and 15, respectively). The fill numbers are even more stark: Kelty went with 1 pound 0.4 ounces of 550-fill-power down in the Cosmic versus 1 pound 9.4 ounces of 600-fill-power down in the Radiant. That’s a big difference! Throw in the cheaper-feeling build of the Kelty, and you aren’t winning by spending $20 less. Grab the Radiant instead. For more, read the Kelty Cosmic Down 20 review.

REI Co-op Magma 15 ($399): The Co-op’s High-End Offering
REI has been winning on the backpacking gear front of late, and the Magma is a staple that has been around as long as we can remember. Filled with 850-fill-power down at a price that undercuts the competition, it’s an interesting alternative and step up from the Radiant. With the Magma, the weight drops down to 2 pounds 3.6 ounces with additional warmth (a Comfort rating of 21 degrees Fahrenheit). It’s not quite as light as true premium options from brands like Sea to Summit, Western Mountaineering, and Feathered Friends, and those brands cut the weight well below 2 pounds for similar levels of warmth. But the Magma is a very respectable, ‘budget, high-end” sleeping bag, if there is such a thing. For a deeper dive, read our review of the REI Co-op Magma 15.

REI Co-op Radiant 20 ($209)
Hanging out in the REI Co-op Radiant 20 backpacking sleeping bag
4.4/5

The Radiant 20 sleeping bag feels more mid-range than its budget price tag would suggest. Yes, it will add around a pound to your kit compared to premium options that double or even triple the cost, but we like its respectable warmth, soft feel, and thoughtful feature set. If you're not counting ounces, you won’t find a better bag for your money. 

Temp Rating
25/13˚F (ISO Comfort/Limit)
Weight
2 lb. 11 oz.
Fill
1 lb. 9.4 oz. of 600-fill down
Shell
Polyester
Shoulder/Hip Girth
66.5/57 in.
Packed Volume
10L (6.7L compressed)
Other Temps
N/A
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Warmth / Weight

3.5/5
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Comfort

4/5
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Features

4/5
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Durability

3.5/5
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Water Resistance

2/5
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Sustainability

4.9/5
Kelty Cosmic Down 20 ($190)
Unpacking the Kelty Cosmic 20 Sleeping Bag
3.9/5

With some of the best price-to-performance on the market, the Cosmic Down is a solid value bag for backpackers who still want good warmth and decent packability. But with a higher-than-average weight and packed size, it’s a stretch to call it a suitable fit for longer backpacking routes. 

Temp Rating
31/21°F (ISO Comfort/Limit)
Weight
2 lb. 7 oz.
Fill
1 lb. 0.4 oz. of 550-fill down
Shell
20D nylon
Shoulder/Hip Girth
62/58 in.
Packed Volume
10.7L
Other Temps
0, 40F
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Warmth / Weight

2.5/5
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Comfort

3.5/5
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Features

3/5
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Durability

3.5/5
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Water Resistance

2/5
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Sustainability

3.1/5
REI Co-op Magma 15 ($399)
Putting REI Co-op Magma 15 Backpacking Sleeping Bag in tent
4.5/5

REI brings premium sleeping bag design to the masses with Magma, an 850-fill-power model at a reasonable price point. Throw in a plethora of size options—the most of any model we’ve seen from a major brand—and there is a lot to like about this bag.

Temp Rating
21/9°F (ISO Comfort/Limit)
Weight
2 lb. 3.6 oz.
Fill
1 lb. 7.3 oz. of 850-fill down
Shell
15D nylon
Shoulder/Hip Girth
62.5/54 in.
Packed Volume
8L
Other Temps
30F
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Warmth / Weight

4/5
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Comfort

4/5
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Features

3/5
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Durability

3/5
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Water Resistance

3.5/5
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Sustainability

4.9/5

Is the Radiant 20 for You?

The REI Co-op Radiant 20 is a great fit for three-season backpackers who want reliable warmth without paying premium-bag prices. It’s relatively heavy by modern backpacking standards, but the tradeoff is an approachable price tag paired with a cozy, well-built design, solid temperature ratings, thoughtful features, and an impressive nine size options to suit a wide range of sleepers. We especially like it for beginner and intermediate backpackers, shorter trips, or anyone building out a budget-conscious kit who still wants dependable three-season performance. That said, if you’re an ultralight backpacker or frequently head out on longer trips where pack weight and packed size really matter, there are much lighter and more compressible options available—just expect to pay significantly more.


Go for it if you want comfortable, reliable three-season warmth at a low price point without many of the usual compromises of a budget sleeping bag.


Pass on it if you’re focused on minimizing pack weight and bulk or only venture out in summer temperatures.

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