Ultralight Sleeping Bag
Therm-a-Rest Parsec 32
$400, 1 lb. 9 oz. (regular)
Sizes: unisex small, regular, and long
It was an amazing spot to sleep under the stars for our last night on an early-April backpacking trip in the Grand Canyon: perched on a plateau high above the Inner Gorge of the Colorado River, gazing across the canyon at the Tonto Plateau and South Rim. We waited until dusk had nearly faded to darkness to lay out our sleeping bags atop our completely exposed, flat cowboy-camping ledges, hoping the relentless, strong wind would abate with evening’s arrival and not threaten to launch our bags to New Mexico—but it didn’t. So I burrowed inside my Therm-a-Rest Parsec 32 for warmth—and only opened my eyes once or twice briefly during the night, enough to glimpse the brilliant glow of the Milky Way.
I stayed perfectly warm sleeping in this bag under the stars (no tent) for five nights on a six-day backpacking trip in the Grand Canyon in April, with lows in the 40s and low 50s F and strong winds some nights that made it feel chillier than the ambient air temps. That experience aligns with the Parsec 32’s EN temperature ratings of 41° F comfort, 32° F limit, and 5° F extreme.
It’s warm enough for typical overnight temps of summer in most mid-latitude mountain ranges or spring and fall in the Southwest canyon country except for people who tend to get cold more easily.
This bag’s nearly 12 ounces of PFC-free, 800-fill down creates four inches of loft, complemented by a warm, adjustable hood that closes snugly around your head and face, plus a draft collar and zipper tube and the thermal efficiency of a mummy design. Therm-a-Rest says the water-resistant Nikwax Hydrophobic Down absorbs 90 percent less water and dries three times faster than untreated, standard down feathers.
In practice, that translates to the Parsec delivering the good warmth-to-weight ratio of high-quality down while also not losing loft (read: warmth) if exposed to moisture on, say, a rainy, multi-day trip with constantly damp air (even inside a tent).
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The bag’s zoned insulation places more down on top than the bottom—not necessarily desirable for side sleepers, but I’m one and my back never felt cold.
The 100 percent recycled, 20-denier shell and lining offer a bit more durability than the 10- and 15-denier fabric used in many ultralight bags at only a slight weight penalty. The shell has a DWR (durable, water-repellent treatment). The two-way, anti-snag zipper, backed by thick fabric strips on both sides, never gets stuck.
At just over one-and-a-half pounds, it weighs less than many similarly rated competitors—and yet it provides a comfortably roomy sleeping experience with dimensions of 62 inches at the shoulders, 57 inches at the waist, and 46 inches at the feet plus a length of 80 inches (in the regular). I never felt constrained shifting around inside this bag.
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The sizing is unisex: Therm-a-Rest no longer makes bags in men’s and women’s models. My take on that is that sleeping bags aren’t boots or packs—gender simply doesn’t matter that much when it comes to a sleeping bag. My wife gets cold very easily and she has virtually always slept in a men’s bag over the 30 years we’ve backpacked together (because I regularly have new bags to test). Her comfort in a bag has less to do with its contours than how warm it is—period.
Like all Therm-a-Rest sleeping bags, the Parsec comes with a compression stuff sack and easily packs inside it, squishing down to just slightly larger than a bread loaf at 6×8.5 inches.
Therm-a-Rest Parsec 32
Lighter and more packable than many bags with the same temp rating, the Therm-a-Rest Parsec 32 delivers good warmth and comfortable space for three-season backpacking, and offers the added value of water-resistant down, at a lower price than top-rated ultralight bags that are just ounces lighter.
For colder temps or cold sleepers, there’s also the warmer Parsec 20 ($450, 1 lb. 12 oz., regular) and Parsec 0 ($530, 2 lbs. 6 oz., regular).
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You can support my work on this blog, at no cost to you, by clicking any of these affiliate links to purchase a Therm-a-Rest Parsec 32 at moosejaw.com or thermarest.com, or any of the warmer bags in the Parsec series at backcountry.com, moosejaw.com, or thermarest.com.
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Want an even lighter three-season bag? See my reviews of the Therm-a-Rest Hyperion 32F, Sierra Designs Cloud 35, and Feathered Friends men’s Hummingbird UL 30 and women’s Egret UL 30.
And don’t miss my picks for “The Best Backpacking Gear” of the year.
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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 my Gear Reviews page at The Big Outside for categorized menus of all of my reviews and my expert buying tips.