Therm-a-Rest Corus 32F/0C Quilt Review

We had to look carefully at every piece of gear this summer as we wanted to cut down our overall pack weight. While we love our regular mummy bag, it was more than we needed between mid-June and early-September.  We were excited to shave off 300g (10.5 oz)  by going to the Therm-a-Rest Quilt.

Disclosure: This post contains references to products or services from one or more of our advertisers. We may receive compensation when you buy one of these products or services. For an explanation of our Advertising Policy, visit this page.

The verdict

Packable, light and warm, the Therm-A-Rest Corus Quilt has earned itself a spot in our packs going forward. It’s the perfect quilt for backpackers looking for a trusty, warm alternative to their traditional sleeping bag.  While it needs to be paired with a down coat as the temperature approaches 32F / 0C, in warmer weather it is a great option for ultralight backpacking.

Thermarest Corus Quilt vs Nalgene Bottle size comparison

Foot box of Thermarest Corus Quilt

Overview

The Therm-a-Rest Corus Quilt is a lightweight down sleeping quilt/duvet/comforter for ultralight backpacking and overnight trips where a full-on sleeping bag isn’t necessary. It’s light and filled with insulating 650-fill hydrophobic down. Therm-A-Rest has updated this backpacking quilt regularly over the years; the newest 2019 version is their most packable yet.

When to use

When backpacking and camping in 3-season weather down to 35F (2C) and you don’t want to pack a full-on sleeping bag. We find it perfect for nights between 35F (2C) and 55F (13C). When it’s below freezing, you’ll probably want something heavier, though we paired with a Patagonia Down Sweater and found it just warm enough. It’s great for hammock camping, too.

Weight

Because the quilt is effectively only about 75% the size of a regular mummy bag, that means it’s about 75% the weight.  The Regular Corus quilt comes in at 1 lb. 4 oz, (570g) and the large is only slightly heavier at 1lb, 6 oz (620g).

Pros

Light and Compressible. At about 1 lb. 4oz (570g), this quilt fits comfortably into any almost pack. The saving of about 300g (11 oz) isn’t great by itself but paired with a lighter sleeping pad, lighter backpack and lighter tent you can see how it’s possible to shave 5 pounds (2.4 kg) from your pack without sacrificing comfort.

3-Season Warmth. Designed for weather between 35F - 45F (2C – 7C), this quilt is great for shoulder seasons and chilly summer nights, thanks to the 650-fill down, baffles sewn throughout the entire quilt, and draft collars on either side.   As it gets closer to 35 F (2C) it’s worth considering wearing a down coat and a toque to bed to keep warm.

“Build A System” Sleeping Pad Compatibility. Thanks to the easily attached loop kit, you can attach the Corus directly to your sleeping pad, or to another quilt for extra warmth and coverage.   We actually haven’t done that, as we enjoy the ability to move around with it not looped in.

Good Price.  Compared to our Western Mountaineering mummy bag, this sleeping bag seems like a great bargain!  That said, this is a quality product, so it is more expensive than heavier options.

Cons

Pricey. Yes, we said it’s a good price, relative to other options.  If you’re new to backpacking you may find the price higher than many 3-season sleeping bags.  You’re paying for an ultralight bag.

Adhesive Pads Could Be Stronger. A minor quibble but something that could be fixed in future updates.

Thermarest Corus Quilt will keep you warm during backcountry trips

Lightweight + compact quilt

The Corus comes in two sizes, a Regular and a Large. The Regular is 72” (183 cm) long and weighs exactly 1 pound, 4 ounces (570g), while the large adds another 6” (15 cm) of length and 2 ounces (57 g) of weight, weighing in at 1 pound 6 oz (620g). There’s an option for almost anyone, even folks above 6 feet (183 cm) tall.

Most backpacking quilts are merely rectangular shaped, like your traditional comforter. The Corus, on the other hand, is tapered like a mummy bag; the latest 2019 model features an even more aggressive taper than previous years.

This tapered design certainly has its benefits – mainly, less fabric used, which means it weighs much less. It also has a few drawbacks, in some eyes. Some folks prefer the wider, squarer style you’d find on most quilts, and don’t like how narrow a mummy bag can be. The space and freedom a large quilt offers is a common reason many people reach for one in the first place. We appreciate the tapered shape, however, as we use it for backpacking; the lighter our kit, the better. In the end, there’s still plenty of room to turn about throughout the night without feeling constrained.

Also new for the 2019 model is an updated footbox. By slipping this enclosed section over your sleeping pad, you can eliminate the cold drafts and gaps in coverage that you might get with a regular square quilt.

The Corus comes with two stuff sacks – a small one for the trail, and a larger bag for long-term storage without compressing. Though not the smallest when packed – much larger than a water bottle, for example – it is comparable to sleeping bags of similar size and weight. It stashes comfortably into the bottom of almost any overnight backpack.

Setting the Thermarest Corus Quilt is easy

Thermarest Corus Quilt review

Ample 3- season warmth

Therm-a-Rest gives the Corus Quilt a Comfort Rating of 45F (7C) and a lower Limit of 35F (2C). Any colder, and you’ll want to bring an additional quilt to make it comfortably through the night. For camping in shoulder seasons and chilly summer nights at elevation, the Corus just plain rocks.

The insulation inside is Nikwax 650-Fill down. NikWax down has a hydrophobic coating which supposedly dries 3 times faster than regular down, repels up to 90% more water, and maintains its natural loft a whopping 60x longer.

To increase warmth without adding weight, Therm-A-Rest sewed baffles through the quilt, essentially attaching the top layer to the bottom and creating air pockets in between. More air means more insulation without added weight.

This baffle design works but creates an additional problem- cold pockets - gaps throughout the quilt where insulation doesn’t fill in and cold air hangs out.

To help fight this, Therm-a-Rest coated their seams with ThermoCapture, their reflective material that traps and reflects your own body heat back into the bag. This reflective coating helps make up for the cold pockets created by the baffling and helps make the Corus the super-warm 3-season bag it is. We daresay you might even find it a bit too much to crawl under in warmer spring nights.

Finally, in order to create maximum warmth, the Corus uses draft collars. Draft collars are essentially long flap pockets that run down the length of the quilt, are filled with down and can be tucked underneath your pad as you sleep, creating a better “seal” and more coverage to eliminate cold drafts and keep more heat in. Draft collars are standard on mountaineering-style quilts and more than welcome on chilly nights, especially if you’re going sans-tent or spending the night in a hammock.

Build a system: sleeping pad + quilt compatibility

One of the Corus’ best features is how easily it can be attached to your sleeping pad or to another quilt. There are 8 snap loops sewn around the perimeter of the bag, with two on the bottom and three on either side. These pair with stick-on adhesive patches, which attach to your mattress loops. You may not even need to use this function in warmer weather, but it’s great to add warmth and security when the temperatures dip.

You can, of course, pair it with another quilt or sleeping bag as you see fit, whether for extra warmth, to create your own sleeping bag, or even an extra-large quilt for two people.

There’s no word on exactly how long the adhesive on these patches lasts, but we have found they can pull off the pad if pulled too strongly. This could happen during the night, if you toss and turn, or if the quilt gets yanked harshly, but they hold up just fine for most uses.

Should you buy the therm-a-rest corus quilt?

This is a great alternative to a sleeping bag, and the Corus Quilt has become our default summer bag for backpacking and camping while the weather is above 35F (2C) at night.  Below that, we will consider either adding a down coat or bringing our warmer Western Mountaineering mummy bag.