Three-Season Sleeping Bag
Sierra Designs Nitro 20-Degree
$320, 1 lb. 15 oz. (regular)
Sizes: men’s regular and long, women’s regular
Choosing between sleeping bags can sometimes feel like getting the names of identical twins right—they look an awful lot alike. With bags, you can compare certain key specs: temperature rating, type and amount of insulation (or fill), total weight, and, of course, the price. Using those metrics, the new Sierra Designs Nitro bags look like a pretty good value, so I slept in the 20-degree Nitro 800 while camping on some cool and windy May nights at Idaho’s City of Rocks National Reserve, and on a three-night, 39-mile backpacking trip in Wyoming’s Wind River Range in mid-September, to see if its performance matches its impressive numbers.
While SD calls it a 20-degree bag, its standardized EN ratings of 28° F (-2° C) for comfort and 17° F (-9° C) for limit offer a good sense of what the average person will find it adequately warm for—although people who get cold easily (including many women) may not want to actually test those temp ratings. Not surprisingly, I found it more than warm enough for nights in the low 40s Fahrenheit; I didn’t have to zip it up completely, even in clammy, rainy weather (sleeping inside a tent). The bag is stuffed with 14.7 ounces of PFC-free, water-resistant, 800-fill-power DriDown, insulation that retains its ability to trap heat even when wet, and will dry out faster than bags stuffed with standard down feathers.
The women’s regular bag contains the same amount of down as the men’s regular, even though it’s four inches shorter, giving the women’s bag a higher density of insulation. That makes it warmer. But given how much more easily women get cold than men, on average, that difference in the bags merely helps justify giving them identical temp ratings.
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The high-quality down helps explain why the Nitro 800/20 Degree weighs in a few ounces south of two pounds—that’s light for a bag with this temp rating. Many lightweight bags achieve a comparable weight partly by literally cutting corners—reducing the bag’s volume, thus using less materials, which naturally translates to less weight but a claustrophobic fit. I’ve slept in too many that were just too tight for even my average build.
To SD’s credit, that’s not the case with the Nitro. It’s mummy cut is more generous than you’ll find in a lot of bags, with a 62-inch circumference at the shoulders, 56 inches at the hips, and 40 inches at the feet (in the men’s regular). I could spread my knees and feet comfortably apart and, as a side sleeper, extend my arms not quite completely straight, but enough to sleep basically in the position I would in my bed. Unfortunately, taller women are out of luck: The one women’s size bag only fits people up to five feet, eight inches.
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I like how, when the bag is completely zipped up, the roomy, adjustable hood fits fairly snugly around my face before I tighten it at all. That also meant I could keep my head outside the hood without letting any cold draft inside the bag. That’s thanks in part to a five-inch-wide draft collar extending all the way to the shoulders. The five-inch horizontal baffles and side wall baffles prevent down from migrating and causing cold spots.
Personally, I’m not a fan of SD’s zipperless foot vent; a couple of times, I inadvertently poked my feet outside the bag when shifting around. Besides, I know at most two or three people who stick their feet outside of their bag when camping; I’ve probably never done that. Still, this feature will appeal to some people—and it comes without additional zipper weight—and accidental foot exposure to cold air wasn’t a regular occurrence in the Nitro.
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On the other hand, I consider the half-length, 40-inch zipper ideal: minimizing weight by eliminating something I don’t need—that is, the ability to cool my legs when sleeping—while making it long enough to easily get in and out of the bag. However, the downside of a half zipper is that you cannot open the bag up fully to use it like a blanket on exceptionally mild nights—but then, most people don’t buy a 20-degree bag for exceptionally mild nights. I found the zipper not entirely snag-proof, but more importantly, it’s very easy to free it if and when it does snag on the inside fabric. The 15-denier shell and liner fabrics help minimize the total weight, but that’s about as light as bag fabrics get, so be gentle with this sack, especially if sleeping out under the stars.
You won’t find any new or special technology in the Sierra Designs Nitro bags—just a comfortable, high-quality, lightweight sleeping bag with water-resistant down at a competitive price. That’s enough reason to get one. SD also makes the Nitro in a men’s 35-degree version ($300, 1 lb. 6 oz.) and men’s and women’s 0-degree ($380, 2 lbs. 8 oz.) versions.
BUY IT NOW You can support my work on this blog, at no cost to you, by clicking any of these affiliate links to purchase a men’s or women’s Sierra Designs Nitro 20 sleeping bag, or one of the other versions, at backcountry.com, moosejaw.com, or sierradesigns.com.
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NOTE: I tested gear for Backpacker Magazine for 20 years. At The Big Outside, I review only what I consider the best outdoor gear and apparel. See categorized menus of all my gear reviews at The Big Outside.