Gear review: Cumulus Lite Line 400 ultralight down sleeping bag

At the centre of all gear lists is a good sleeping system. Ideally you’ll want something small, light, practical, reasonably priced and with the correct warmth credentials. In real life of course you always have to make some sort of compromise.


While planning a trek in Peru it became apparent that a new sleeping bag was in order. I needed something light for traveling that would allow me to spend a few nights below zero. My search took me to a few lesser known manufacturers. The big names available in Europe, like Rab, Mountain Hardwear or Mammut to name a few, all had great options but at prices that did not suit my budget at the time. I ended up buying the Cumulus Lite Line 400. I had read a thread on a small forum about it, the specs on paper looked great, the price was very competitive.


You can read the full spec sheet on the Cumulus Lite Line 400 page. The interesting bits are: Pertex Quantum fabric inside and out, 400g of Polish down 850 cuin, rated 2 ˚C comfort, -4 ˚C limit and -20 ˚C extreme. Total weight: 755g.

This bag has been to Peru, Bolivia, the Great Atlas in Morocco and on the roof of Africa: Kilimanjaro. It has been used with tents, hammocks or on the floor of some very rural accommodations. I think it is time to write about it.


In terms of numbers the Cumulus Lite Line 400 really hits the sweet spot for 3 seasons backpacking and for traveling. Down packs legendary small. The size of the packed bag is about 25cm x 17cm. A comparable synthetic bag would be easily twice the size and 1.5 times the weight. Even compared to other down sleeping bags, the Cumulus Lite Line 400 reaches a very good weight/size ratio due to the use of some of the highest quality down on the market.


I was a bit concerned about the fabric at first. Pertex Quantum, when you see it in the flesh, does not convey a reassuring feeling of strength. It is crazy light per square meters though (35g/m2) and very soft. Just what you want to make an ultra light sleeping bag. I always take great care when handling my gear and, after 5 years of decent use, the fabric of the bag is not showing any signs of weakness. There is the odd feather coming out now and then, which is pretty normal for a down bag and a few loose threads only. You’ll have to be very careful of course because any sharp object like crampons, pointy rocks and bushes would open up the Pertex fabric in no time. I am not holding it against the Cumulus Lite Line 400, when you want low weight, resistance is the first compromise you’ll have to make.


This sleeping bag also has all the bells and whistles to keep you warm at night. The elasticated hood can be fitted tight to keep warm air inside and around your head with the pull of a draw-cord. There is a small baffle around the neck for air tightness. Another full-length baffle follows the side zip to make sure cold air does not sting you from the side. In practice this one works well but tends to get caught in the zip when opening/closing the bag. That could be a cause of damage of the Pertex Quantum fabric if you are not careful. The footbox is extra filled and in truth too warm for me. The two-way zip will let you ventilate from the bottom if needed. I think all sleeping bag should have two-way zips. I’ve used that feature from the Cumulus Lite Line 400 on numerous night and I would not choose a bag without now. The specs put -4ºC as the limit and in my case this seems to be accurate. I spent a few night at around -5˚C in the Andes and I slept well once I added a light fleece to my long sleeves mid weight merino base layer. I am also a warm sleeper so you’ll have to adjust for your personal type. The sleeping pad used Above 10ºC is really too hot and anywhere just above zero is perfect for a good night’s sleep without having to add too many layers.


The mummy shape is a bit tight around the feet but otherwise ok. 77cm at the shoulders and 51cm at the footbox. You can choose the side of the zip when ordering on Cumulus’s website and two bags can be joined together if the zips are on the opposite sides. A nice touch if you bring your partner with you. An internal pocket, at shoulders height will be able to hold a smartphone, headlamp and a snack or two / phone, passport and wallet if you are travelling.

Delivery for two Cumulus Lite Line 400 took about two weeks. The bag comes with a small stuff sack and a large one for storage.

In terms of competitors you have the Rab Neutrino 400, 860g, limit -3˚C. Heavier and more expensive but with Hydrophobic down. Very similar is the Mountain Hardwear Ratio 32, Hydrophobic down, reasonably priced. The Yeti VIB 400 could also fit the spec bill but is more expensive and heavier. There are of course a lot more options but I think those put the Cumulus Lite Line 400 in perspective.


Final words about the Cumulus Lite Line 400

There is very little wrong about the Cumulus Lite Line 400. I can’t actually find anything I would change. For the price it has all the specifications that matters. It’s light, warm, small when packed and comfortable. I can’t find anything available in Europe today that matches the same specs and price. With the popularisation of Hydrophobic down one might wish to look for gear that uses it. I believe that when you are careful enough and know how to manage condensation in your shelter, hydrophobic down is not that big a step forward.