Kelty Cosmic Down 20 Sleeping Bag vs Western Mountaineering MegaLite

Editorial Team
Last modified at May 24, 2026
When it comes to backpacking, a reliable sleeping bag is essential for a good night's rest in the great outdoors. The Kelty Cosmic Down 20 and Western Mountaineering MegaLite are two popular options that cater to different needs and preferences. This comparison will help you understand the strengths and weaknesses of each sleeping bag, ensuring you make an informed decision based on your specific requirements.

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Kelty Cosmic Down 20 Sleeping BagWestern Mountaineering MegaLite
Cosmic Down 20 Sleeping BagMegaLite
Weight

Short: 35 oz Regular: 43 oz Long: 47 oz

5'6": 23 oz
6'0": 24 oz
6'6": 25 oz

Fill Power

550

850+

Packed Size

Short: 1029 cu in Regular: 1352 cu in Long: 1512 cu in

5'6": 432 cu in
6'0": 583 cu in
6'6": 583 cu in

Shell Material

Recycled 20D Nylon Taffeta

12D ripstop nylon

Fits Up To Height

Short: 72 in Regular: 78 in Long: 84 in

5'6": 63 × 56 × 39 in
6'0": 64 × 56 × 39 in
6'6": 65 × 56 × 39 in

Warranty

Lifetime

Manufacturer defects covered for unlimited time

Zipper Type

Quad-stitch anti-snag

Full-length #5 YKK

Down Treatment

DriDown

Ethically-sourced premium goose down

Baffle Construction

Trapezoidal

Continuous baffles

Foot Box Shape

Expanded, natural fit

Mummy

Hood Type

Insulated, adjustable

Top collar with adjustable draw closure

Water Resistance

PFAS-free DWR

Water-resistant

Draft Collar

Full draft tube and collar

Insulated draft tube and top draft collar

Temperature Rating

20°F

30°F

Comfort

Cosmic Down 20 Sleeping Bag

4.2/ 5.0

MegaLite

4.7/ 5.0

Comfort is crucial for a good night's sleep, especially after a long day of backpacking. A comfortable sleeping bag can make a significant difference in your overall camping experience. The Western Mountaineering MegaLite excels in this category with its spacious mummy design, providing ample room to move around, which is ideal for side sleepers or those who dislike tight quarters. The ultra-smooth nylon taffeta liner and passive top collar enhance the cozy, silk-like feel. While the Kelty Cosmic Down 20 offers a cozy fit with ample leg room, some users find the shoulder area a bit tight. The MegaLite's thoughtful features and roomier design make it the winner in comfort.

Warmth

Cosmic Down 20 Sleeping Bag

4.8/ 5.0

MegaLite

4.6/ 5.0

Warmth is a critical factor for backpacking sleeping bags, as it directly impacts your ability to stay comfortable in cold conditions. The Kelty Cosmic Down 20 is highly praised for its warmth, keeping users comfortable in temperatures down to 20 degrees. It uses high-quality down insulation that provides reliable warmth even in chilly conditions. The Western Mountaineering MegaLite, while also warm, has a temperature rating of 30°F and uses 850+ fill power down with continuous baffles for adjustable insulation. However, the Cosmic Down 20's slightly better temperature rating and consistent warmth make it the winner in this category.

Durability

Cosmic Down 20 Sleeping Bag

4.9/ 5.0

MegaLite

3.6/ 5.0

Durability ensures that your sleeping bag can withstand the rigors of backpacking and last for many trips to come. The Kelty Cosmic Down 20 stands out with its high-quality materials and construction, ensuring long-lasting durability. Users report no significant issues with durability, making it a reliable choice. The Western Mountaineering MegaLite, while backed by a lifetime warranty, has a more delicate 12-denier nylon shell that can be prone to snags and tears with rough use. The Cosmic Down 20's robust construction and positive user feedback make it the winner in durability.

Packability

Cosmic Down 20 Sleeping Bag

4.4/ 5.0

MegaLite

4.7/ 5.0

Packability is essential for backpackers who need to save space and reduce weight in their packs. The Western Mountaineering MegaLite excels in this category, compressing easily into a compact size comparable to a large grapefruit. Its lightweight design and included stuff sack ensure effortless packing and carrying. The Kelty Cosmic Down 20, while also appreciated for its lightweight and compact design, does not pack down as small as the MegaLite. The MegaLite's superior packability makes it the winner in this category.

Versatility

Cosmic Down 20 Sleeping Bag

3.1/ 5.0

MegaLite

4.9/ 5.0

Versatility allows a sleeping bag to adapt to various conditions and preferences, making it suitable for different environments and seasons. The Western Mountaineering MegaLite shines in this category with its continuous baffles and full-length zipper, allowing you to shift down or vent as needed. This adaptability makes it perfect for three-season use and various temperature conditions. The Kelty Cosmic Down 20, while a solid sleeping bag, lacks the same level of versatility due to fewer user-reported aspects. The MegaLite's adaptability and user-friendly features make it the clear winner in versatility.

Ease Of Use

Cosmic Down 20 Sleeping Bag

3.7/ 5.0

MegaLite

4.9/ 5.0

Ease of use is important for a hassle-free camping experience, allowing you to set up and adjust your sleeping bag quickly. The Western Mountaineering MegaLite excels with its full-length YKK zipper and thoughtful design details like a velcro zipper cover, ensuring smooth, snag-free operation. Users find it incredibly easy to use with simple adjustments. The Kelty Cosmic Down 20, while also easy to use with features like a two-way zipper and velcro closure, does not match the MegaLite's level of user-friendly design. The MegaLite's superior ease of use makes it the winner in this category.

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Conclusion & Final Verdict:

After comparing the Kelty Cosmic Down 20 and Western Mountaineering MegaLite sleeping bags, it's clear that each has its strengths. The Kelty Cosmic Down 20 excels in warmth, durability, and water resistance, making it a great choice for colder conditions and rough use. On the other hand, the Western Mountaineering MegaLite stands out in comfort, packability, versatility, and ease of use, making it ideal for backpackers who prioritize space-saving and adaptability.

Choose the Kelty Cosmic Down 20 if you need a durable, warm sleeping bag for colder temperatures. Opt for the Western Mountaineering MegaLite if you prefer a lightweight, versatile, and easy-to-use sleeping bag that packs down small.

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