Even with the recent addition of Feathered Friends products to our sleeping bag reviews, the MegaLite still receives our Editors' Choice Award. It accomplished this with few, if any, changes from its previous versions. Why change what's perfect, right? In all seriousness, the MegaLite's now faces stiffer competition than ever. We still love its spacious dimensions, low weight, and cozy warmth. However, if minor issues with the zipper and hood aren't addressed, it could potentially lose its throne.
The MegaLite is our favorite backpacking sleeping bag because it performs well in virtually every way and is suitable for almost any outdoor activity.
The MegaLite is filled with down advertised as "850+" fill power. However, when trying to compare this with other bags it's important to understand that this is a conservative estimate. Western Mountaineering claims the actual fill power rating of their down is "almost always above 900." They report the lower 850+ number to be on the safe side and indicate the level of loft that's expected once the down is slightly compressed within the fabric of a sleeping bag or garment. In our tests, the 13 ounces inside this bag felt every bit as lofty as the higher rated down of the Feathered Friends Swallow and Rab Mythic 400.
Although Western Mountaineering doesn't have their bags EN tested, we believe the MegaLite outperforms its 30°F temperature rating. Our testers feel like it provides comparable warmth to an average bag that receives a 20° EN Lower Limit rating. This makes it ideal for use in the shoulder seasons and the cooler nights of summer.
Check out the difference between budget down and ultra-premium. The 850+ FP down of the MegaLite (right) lofts 6 inches upward, while the KSB's 650 FP down (left) lays nearly flat on the ground.
The size long we tested weighs in at an impressive 1.63 pounds on our scale. This places it close to the front of the pack. When you also factor in its considerable warmth, it results in an impressive warmth-to-weight ratio.
Its more comfortable, wide dimensions, however, do require additional materials. The slimmer Feathered Friends Hummingbird UL achieves similar warmth while weighing a few ounces less. Feathered Friends' included stuff sacks are also lighter than Western Mountaineering's, giving a packed Hummingbird an overall four-ounce edge over the MegaLite.
The MegaLite's 64" shoulder girth is so roomy that it can extend past the sides of a backpacking sleeping pad. On the occasional open bivy, this may be a minor problem, but it's not really an issue inside a tent.
The characteristic that ultimately nudges the MegaLite past its competitors is its comfort. With several extra inches of upper body girth, even our largest testers didn't find this bag constrictive. Although this adds a few ounces, the added weight will be worth it for most users, especially when you consider an ultra-premium down bag can maintain its loft and performance for a long, long time. Think about it — ten years from now, you might find yourself appreciating the extra room?
Another subtler aspect of MegaLite's comfort that distinguishes it from its closest rival, the Feathered Friends Hummingbird UL, is the shell fabric. Both bags feature shells that are similarly soft and weather resistant. However, the Hummingbird is protected by Pertex Endurance fabric that was strangely noisy. At least one tester claimed the crinkling sounds disturbed their sleep. Similar noise issues were not observed with the ExtremeLite fabric found on the MegaLite.
The WM UltraLite (left) and MegaLite (right) both come with simple drawstring stuff sacks. To fully enjoy their impressive warmth-to-volume performance you will need to get a third-party compression sack.
In our tests with an aftermarket compression sack, this bagged compacted to a respectable packed volume of 7.2 liters. Although this wasn't the smallest size we saw, it was the smallest for bags that provided a similar level of warmth.
To take advantage of this benefit, however, you will need to purchase a third-party compression sack. The simple drawstring stuff sack of the MegaLite comes with does an OK job at compression but will still leave you with a bag that occupies a couple of extra liters in your backpack.
All "full-length" zippers are not equal. The Feathered Friends zippers (red) are noticeably longer than the Western Mountaineering (blue) or Nemo (orange) zippers.
Although the down insulation isn't ideal for wet conditions, the MegaLite has enough versatility for many other applications. Its spacious dimensions ensure there is plenty of room for wearing additional layers on colder nights. Meanwhile, its full-length zipper gives you good venting options when it's warmer out.
Ultra-premium down bags, like the MegaLite, also offer versatility advantages due to their continuous horizontal baffle construction. This means the down insulation is contained within fabric tubes, or baffles, that are perpendicular to the length of the bag. In addition, these baffles are continuous because they're uninterrupted by seams of stitches. This design gives you the ability to move feathers to the top or bottom of the bag depending on conditions. On cooler nights shifting feathers to the top will trap additional heat. On warmer nights you can do the opposite to avoid overheating.
Here you can see how the author has moved feathers inside the bag from his left to his right. Doing so lets you adjust the amount of insulation the bag provides for warmer or colder nights.
Both Western Mountaineering bags, however, receive a slight versatility deduction because their "full-length" zippers end ten inches short of the end of the bag. Although this doesn't really affect their venting ability, it does limit their use as a blanket or quilt. The Feather Friends' zippers, in contrast, extend four inches farther. This may not sound like much, but it has a real impact on the possibility of sharing one bag between two people.
We love the Western Mountaineering (top) and Feathered Friends (bottom) zippers because they snag so rarely. Both could be improved, however, with a pull tab on the inside of the bag.
Features and Design
All the Western Mountaineering and Feathered Friends bags, including the MegaLite, feature a flexible internal strip of plastic along the length of their zippers. This strip gives the fabric next to the zipper critical stiffness that prevents it from snagging in the zipper. Western Mountaineering zippers, however, could be improved by incorporating anti-snag slides and an internal pull tab.
Another small issue is the hood. It is anchored at the zipper closure with a weak piece of velcro that felt awkward to use. When cinched tight, the hood only provided below average comfort.
The velcro tab used to close the hood is kind of awkward to connect and not 100% reliable for keeping the bag closed.
All ultra-premium down products have staggering price tags. The MegaLite is no exception. However, for dedicated backcountry travelers, the performance benefits should be worth the cost. Also, in our experience, premium down holds up better to being repeatedly compressed than lower-quality down or synthetic insulation. This means that over the full lifetime of a bag, a MegaLite could ultimately be cheaper per use than some lower priced bags.
In the best backpacking sleeping bag review, there can only be one overall winner. Due to impressive performance across all rating criteria, along with best-in-class comfort, the Western Mountaineering MegaLite earns our Editors' Choice Award. Although it's certainly pricey, if we could only have one bag for all our adventures, this would be it. The competition, however, was incredibly close. So depending on your preferences, there's a chance another ultra-premium down bag could be a better choice.
A hearty congratulations to Maria Alvarez for making what we think is the best backpacking sleeping bag in the world!