Reviews You Can Rely On

Rab Ascent 900 Review

This bag is heavy on the warmth and light on the wallet
rab ascent 900 sleeping bag down cold weather review
Credit: Rab
  • 1
  • 2
  • 3
  • 4
  • 5
Price:  $325 List
Manufacturer:   Rab
By Matt Bento ⋅ Senior Review Editor  ⋅  Apr 23, 2018

Our Verdict

The Rab Ascent 900 is a great bag for those looking to camp in colder weather but don't want to pay the high price for a lighter bag. This bag is only slightly tapered and feels wider than other bags with similar measurements and more taper. It's comfortable for back and side sleepers. While not the lightest bag, the highly weather resistant shell, lofty 650 fill power duck down, and excellent features make it a great deal. For a cool $360, you can jam out into the hills for some fun without freezing at night when the temps are dipping into the low teens.
Weather resistant
Zipper snags
Product Updated Since Testing
The Ascent 900 has seen some minor updates. See the latest incarnation of the bag in the photo above and read on to see what's changed.

Our Analysis and Test Results

2018 Updates

As of 2018, the Ascent 900 has incurred some changes since we tested it. Namely the use of Pertex Quantum fabric instead of the Pertex Microlight that was previously used as the outer shell of the bag. These two fabrics are both made of 100% polyamide nylon, but the Quantum fabric is almost 50% lighter than the Microlight - the Pertex Quantum weighs in at 35g/m2, while the Microlight is 60g/m2 (grams per square meter). The bag still features 900 grams of 650 fill power down. The liner of the bag is now red instead of grey, and the price of the bag rose $10, up from $350 to $360, which we think is still a killer deal for a great bag. But, since we haven't laid down for a night's rest in the new Ascent yet, all of the following text refers to the bag we initially tested in 2017.

Hands-On Review of the 2017 Rab Ascent 900

This budget-priced bag doesn't cut corners where it counts. While it's not as light as the Feathered Friends Snow Bunting or the Western Mountaineering Versalite, or as warm as the Antelope MF, it is just light enough for shorter trips into the backcountry where it will do its main job sufficiently, keeping you warm and dry, without draining your bank account.

rab ascent 900 sleeping bag down cold weather review - this bag puts 37oz of duck down between you and the cold world.
This bag puts 37oz of duck down between you and the cold world.
Credit: Matt Bento


Warmth is perhaps the most important consideration in a cold weather bag, and our testers found that this budget-friendly bag kept them toasty on nights in the upper teens, and downright hot on some nights in early spring. Fortunately, there is a two-way zipper for venting. This bag isn't as warm as lower rated, more expensive bags like the Feathered Friends Snowbunting or the Editors' Choice, the Western Mountaineering Kodiak MF.

We found that wearing a down jacket inside the bag helps to fill up the dead space left by the roomy cut when pushing into lower temperatures. Boots and layers shoved into the wide foot box also help insulate our feet when they felt cold from the extra space.

rab ascent 900 sleeping bag down cold weather review - inside the ascent 900, our tester could sleep pretty comfortably on...
Inside the Ascent 900, our tester could sleep pretty comfortably on his side or stomach, but sleeping on his back is the most optimal position for staying warm, and well oxygenated.
Credit: Jenni Snead


The Ascent 900 features 650 fill duck down — 31.7oz of it to be exact. Duck down doesn't have as much fill power as the high-quality goose down found in the similarly weighted and much warmer (and more expensive) bags. This bag doesn't have the best warmth-to-weight ratio, but the Ascent erred in favor of warmth, and our testers agreed that carrying some extra weight was worth the effort. Carrying a few more ounces is better than spending the night shivering in a limp, un-lofty sack.


This generously cut bag takes a middle of the road comfort metric. It is roomy in the foot box and in the hood. Our testers that sleep on their backs had plenty of room to cross their legs or splay out their feet, but the middle and shoulders of the bag weren't wide enough to sleep as comfortably on their sides as in the hefty Western Mountaineering Kodiak. The hood is deep and comfortable, keeping our noggins toasty when cinched tight. We wished that the draft collar was just a little bit thicker.

Packed Size

Again, duck down doesn't compress quite as well as its loftier goose cousin, but the Ascent still compresses better than heavier, less expensive bags.

rab ascent 900 sleeping bag down cold weather review - included with this bag is a quality compression sack that reigns in...
Included with this bag is a quality compression sack that reigns in all the loft so you can have more room in your pack. Also included is a big, cotton storage sack. Use it, and your bag will thank you with a longer life.
Credit: Jenni Snead

The Pertex shell feels tougher than the shells on some of the lighter bags, which is great if you're like our lead tester and prefer to forego the stuff sack and just cram the bag in the bottom of your pack, stuffing the rest of your gear on top of it.

This bag is one of the few models that comes with a compression sack, making it easier to pack it as tightly as possible.

rab ascent 900 sleeping bag down cold weather review - while not the smallest packed bag, the ascent still stuffs down to a...
While not the smallest packed bag, the Ascent still stuffs down to a size that easily fits in a 50 liter pack.
Credit: Matt Bento


The Ascent 900 has similar features to some of the more expensive bags in our review. The full-length draft tube running the length of zipper prevented our testers from feeling cold and moisture on the zipped side of the bag. The draft collar hangs down nicely over the chin, but it doesn't have its own dedicated cinch cord like on the Rab Neutrino 800, or the Nemo Sonic.

A small zipper accesses the stash pocket located within the draft collar, which is large enough for a headlamp and a phone. The zipper is lined with an anti-snag tape, but we still managed to get the zipper frequently snagged in the dark of night. The hood features a cinch cord that tightens down around the top and the bottom of the hood. This bag arrived with a large storage sack and compression sack. We found that the Ascent 900 can compress much smaller in our smaller compression sack than in the included stuff sack.

rab ascent 900 sleeping bag down cold weather review - climb on into a spacious bag with a warm draft collar and a deep...
Climb on into a spacious bag with a warm draft collar and a deep hood. We found bags with a lighter color interior took a bit longer to dry than bags with black insides like the Feathered Friends Snowbunting.
Credit: Matt Bento

Weather Resistance

We found this model to be significantly more weather resistant than the Kelty Cosmic Down. For the price, we are super impressed that this bag holds up so well against frozen and not so frozen precip. The Pertex microlight shell fabric does an excellent job of repelling water. In our light rain testing, water beaded and puddled on top of the bag, but didn't absorb through the shell or the seams.

In our submersion tests, we found that the Ascent absorbed slightly more water than the Nemo Sonic. The Ascent's 650 fill power duck down features Nikwax hydrophobic treatment, which may help the bag dry out faster. Our testing showed that the most important factor in retaining loft and speed of drying time is the water resistance of the shell fabric, and the Ascent does this as well as its lighter weight and more expensive competitor, the Western Mountaineering Versalite.

rab ascent 900 sleeping bag down cold weather review - this bag has no trouble shedding water thanks to its pertex shell...
This bag has no trouble shedding water thanks to its Pertex shell fabric.
Credit: Matt Bento


Due to its weight, comfort, and great weather resistance, the Rab Ascent 900 is a great value. This bag has some killer features. It has weather resisting capabilities equal to bags that are almost twice the price. It is heavier than some of the more expensive bags in this review, but will still keep you warm when the temps start to drop.


This bag is a steal for those who want to camp in the cold without breaking the bank. This contender is an incredible value and scores higher in all the metrics than the super budget friendly Kelty Cosmic Down 0. We feel it's an awesome balance of value and performance.

Matt Bento
You Might Also Like

Ad-free. Influence-free. Powered by Testing.

GearLab is founded on the principle of honest, objective, reviews. Our experts test thousands of products each year using thoughtful test plans that bring out key performance differences between competing products. And, to assure complete independence, we buy all the products we test ourselves. No cherry-picked units sent by manufacturers. No sponsored content. No ads. Just real, honest, side-by-side testing and comparison.

Learn More