Of course, winter sleeping bags (sleeping bags) are indispensable when spending nights in the harsh cold, such as in a tent in the winter mountains.
Restoring your exhausted body with a warm and comfortable sleep can have a major impact on your next day's behavior. On winter mornings, the inside of the sleeping bag is so comfortable that you can't even get out of it.
On the other hand, mountains are all year round, but if you spend the night with inadequate bedding, you may be unable to sleep due to the cold, wake up multiple times in the middle of the night, or in the worst case scenario, you may end up with hypothermia. In that sense, sleeping bags are expensive, but it is one of the gears that you need to choose carefully.
So, what kind of sleeping bag should I choose? Since it is used for freezing low temperatures, it is only natural that it has high heat retention. If you're camping or sleeping in a car, you can just carry something warm even if it's a little bit bigger. However, this is not the case when used for mountain climbing. The question is how efficiently and without compromising this warmth, it becomes possible to achieve its convenience and safety.
As an aside, the down padding used in winter sleeping bags has specifications that are comparable to those of poorly sophisticated high-end down comforters, allowing you to enjoy the ultimate sleeping comfort even in the lower reaches.
So, this time, in order to find a product that can be absolutely trusted in the winter outdoors, we have compared and examined the winter models from the three most popular domestic manufacturers that Japan is proud of.
Both sleeping bags are models that are expected to be widely used in most severe winter mountains, with a 2,000m class domestically. I was surprised by the spirit of making products, not only in terms of heat retention, but also in the details of the product-making spirit that is created from the user's perspective.
table of contents
table of contents
- About the items we compared and tested this time
- Test results and spec comparison table
- Impressions of each model
- Detailed reviews of each item
- summary
Sleeping bags compared this time
Here are the three models we compared this time. It is a well-known three major brands of authentic outdoor and mountain climbing sleeping bags. There are many excellent models overseas too, but in Japan, these three companies are so strong that they cannot enter the market, making them a brand with a high level of reliability in basic performance.
That's why don't you want to compare which of these three is better (or worse)? That's the theme of this comparison test!
Although it is called a winter sleeping bag, there are various models depending on the quality and quantity of down, but the current usage environment is that it is a model that can be used well in mountains during the harsh winter (2,000m class south of Tohoku), so we have picked out a lighter model that can be used for mountain climbing with a limit of around -10°C.
- ISUKA AIR 630EX
- mont-bell alpine down hugger 800#1
- NANGA UDD BAG 630DX
Test environment
The test period lasts for two seasons from 2018 to 2019, and is in the harsh winter in Hokkaido. The environment is used in tents, sleeping in the car, or outdoors in strong winds. When I sleep, I wear a base layer, fleece, a down jacket, and a base layer and trekking pants.
I also tried to sleep in my sleeping bag when I went to bed, in order to verify the comfort of my sleeping bag at home. In total, you'll be sleeping in your sleeping bag for about two months!
The following five points were set as indicators for review of the evaluation items.
- Thermal insulation...needless to say, this is the most important item in a winter sleeping bag. Of course, it doesn't mean that just warm is fine no matter how heavy it is. Furthermore, this is merely a comparison between the models this time, so it cannot be said for all models in the brand.
- Weight: I want to keep the weight down as much as possible when I use winter mountain equipment that is bulky. However, this also balances with heat retention, and it's not just that it's light enough.
- Comfort: Check how comfortable you are sleeping. It can be a bit distracting when it becomes extremely cramped to achieve both weight and heat retention.
- Portability (storageability): Just like the above weight, it is something you should not miss from the perspective of carrying it around.
- We check how close the user is to the actual situation, such as functionality, water repellency, ease of use, and ability to respond to poor conditions.
Test results and spec comparison table
If you find it difficult to see the table because it is lightweight for smartphones, click here
| comprehensive evaluation | AAA | AAA | AA |
|---|---|---|---|
| item |  |
 |
 |
| Reference price | 51,840 yen | 37,800 yen | 51,840 yen |
| This is ◎ |
|
|
|
| This is △ |
|
|
|
| Thermal insulation | ★★★★★ | ★★★★☆ | ★★★☆☆ |
| weight | ★★★☆☆ | ★★★★★ | ★★★★☆ |
| Comfort | ★★★★★ | ★★★★☆ | ★★★★☆ |
| Portability | ★★★☆☆ | ★★★★☆ | ★★★★☆ |
| Functionality | ★★★★☆ | ★★★☆☆ | ★★★★★ |
| Specs | |||
| item | ISUKA AIR 630EX | mont-bell alpine down hugger 800#1 | NANGA UDD BAG 630DX |
| Manufacturer's temperature range (℃) |
*ISUKA's own standard |
*EN13537 |
*EN13537 |
| Size (cm) | 80 (shoulder width) x 213 (total length) cm | Up to 183cm | Maximum length: 210 x Maximum shoulder width 80/cm (up to 178cm tall) |
| Actual measured weight (including storage bag) | 1150g | 924g | Approximately 1,080g |
| Storage size (cm) | φ20×34cm | φ17 x 34cm (6.2L) | φ17 x 31cm Accessories: Shoulder warmer included |
| material | 100% nylon (Nylon 66) | Outer material: 10 denier ballistic R air light [Polcatex R processing] | 15dn nylon shinre water repellent treatment |
| Down quality | 800 Fill Power White Goose Down (90/10) | 800 fill power EX down | 770 Fill Power European Duck Down (90/10) Super Water Repellent |
| Down amount | 630g | not clear | 630g |
| Zipper specification | YKK anti-biting zipper | R (right) zipper | YKK biting zipper |
Impressions of each model
ISUKA AIR 630EX
This is ◎
- Excellent heat retention
- touch
- Fit
- The zipper is very smooth
This is △
- The hood is shallow
- Storage size and weight
The shoulder warmers that wrap around the front and back of the neck fit naturally without any adjustments.
In a nutshell, it's "simple and robust." This model focuses on sleeping comfortably, and is packed with high heat retention and simple functions, making it a model that can be used safely even in the harsh winter.
The supple texture on the inside and the 800FP white goose down, which has excellent padding, not only allowed you to sleep well until the morning even during field tests at 15 degrees below zero, but also provided an exquisite sleeping experience that is comparable to a high-end down comforter.
In my personal opinion, it is the best of the three models in terms of heat retention. In particular, there was a lot of down sealed inside my feet, so my feet were still slurping until morning. From here, I think that the manufacturer's specifications, "minimum operating temperature -15°C," is probably close to the "limit temperature" according to the EN standard.
Unlike the other two models, the U-shaped shoulder warmer that wraps around the neck is not a drawstring type, but the soft fabric fits well so you won't be bothered. Personally, I think I prefer not having a drawcord to it as simple as it doesn't get in the way.
In addition, the draft tube located on the zipper part firmly prevents cold air from entering the zipper. The zipper with a mitigation reduction function generally works well, but since there was no biting at all, I felt that there was still room for improvement.
The waterproof test showed excellent water-repellent properties of the outer material, and although it continued to apply water in the shower for about 3 minutes, it did not show any penetration into the down. However, once the down got wet, it became sluggish afterwards, and I felt it would be difficult to use it on the field.
The hood is the shallowest of the three models, and the entire head is not the type that can fit completely inside, so when used outdoors in strong winds, the cold that the head and face inevitably suffered from.
The price is the highest this time, but overall I think it's a sleeping bag that has the heat retention, comfort and functionality that matches it. As expected from Japan's proud brand, ISUKA. This model was a model that I would confidently recommend.
mont-bell alpine down hugger 800#1
This is ◎
- Stretchability
- Storageability
- light
- Water repellent performance on the surface
This is △
- Fit around the neck
- Zipper biting
Montbell is the only one with a double draft tube that prevents cold air from the zipper.
It's the cheapest of the three models, so to be honest, I was quite disrespectful at first, but to put it simply, it was a good idea to be disappointing. It's truly cost-effective.
The first thing that surprised me was the high insulation properties. The sleeping bag, which is packed with 800FP EX down, boasting high resilience, was not as good as ISUKA, but it felt warmer than Nanga, which has the same temperature mark. This subtle difference seems to be more about the quality of the down, but rather the overall feel of the various mechanisms that prevent the intrusion of cold air, such as the high density outer fabric "Balistic Air Light", the neck baffle around the neck, and the "double draft tube" that is attached to hold a zipper.
Above all, Montbell's unique "spiral stretch system" allows even authors who have trouble sleeping with poor sleeping positions to move comfortably inside their sleeping bags, providing a unique sleeping comfort. I had plenty of time to change clothes inside my sleeping bag, and I wear cross-legged clothes, so I can wear my sleeping bag even when I'm not sleeping during the cold season. This is also warm and easy to use.
The included staff bag also uses the same spiral stretch system as the sleeping bag, which not only reduces stress when storing, but also changes shape to fit into the dead space inside the backpack, making packing very easy.
Unfortunately, the chuck bites frequently. In particular, when closing the zipper from inside the sleeping bag, the bite occurs once in three times, and if you force it to close it, there is a risk of damaging the fabric, so the more you do it carefully, the longer it takes and I feel very stressed.
Overall, it is lightweight, cost-effective, and has unparalleled comfort, such as stretching functions, but I have the impression that it is not as good as the other two in terms of sleeping comfort and the detailed parts construction.
NANGA UDD BAG 630DX
This is ◎
- touch
- Large hood
- Water-repellent down
- Smooth zipper that is hard to bite
- Storage size
This is △
- Thermal insulation
- Cold air from the zipper
The Nanga biting reduction zipper was the best this time around.
Speaking of Nanga, it's a very grateful "permanent guarantee." With this system, users will be trying to cherish it for the rest of their lives. The UDD BAG 630DX has been released by Nanga. DX down made from white duck down from Europe washed in Japan. This UDD is a water-repellent down that is treated with a super water-repellent finish, and is made into a water-resistant down that "passes through moisture but does not absorb water."
I'm concerned about the water resistance, but first, I'll talk about heat retention. The insulation was satisfactory at the specified temperature range (up to -10°C). It also has a great mechanism to prevent cold air from entering, such as the neck area and draft tube, and the large hood warms the head, making it a great piece. However, when comparing the temperature exceeded the limit and in harsher environments such as low temperatures of around -15°C and strong wind conditions, it is also true that this comparison was the easiest to feel the cold air. I've been feeling the cold air coming in, especially from the zipper and the feet. There may be a difference in quality down quality, but I was surprised that it felt colder than the same Montbell based on the EN standard.
Now, regarding the water resistance, it's a concern, when you submerge the down underwater, it will instantly rise. After repeating it several times, the result was the same, and the entire down was a little wet, but it didn't become slurpy. The other two models were not only shining after repeating them a few times, but rather became shaky, so I was surprised by the results. Of course, wet down will lose its heat retention, so if you use a UDD that repels a little moisture and moisture, it is unlikely to lose its heat retention even if used in harsh environments for a long time.
The zipper is a luminous type with a light-emitting design that reduces biting. It's very helpful that it's excellent visibility even in the dark. Bite reduction also works well. In reality, if you close the zipper with force without stretching the fabric, it will bite at a certain rate.
Although the heat retention of the three models is slightly inferior, it is one of the things that has an unparalleled charm, such as the ease of use and security of the water-repellent down, the fine details including the luminous zipper, and the reliability of the life-saving warranty system.
Next page: Go to detailed reviews of each item
On the previous page, we introduced a ranking of the models we compared, a list of ratings and specs, and recommendations based on them. From here, we will explain what criteria were used to evaluate the evaluation, and why it was evaluated in that way.
Detailed reviews of each item
Thermal insulation
Heat generated inside a sleeping bag has the tendency to move and rise from warm areas to cold areas. The key to a warm down jacket is how effectively it can retain heat by preventing this warm air from escaping and by using the sleeping bag, which also acts as an insulating layer between the warm air and the outside air. For this reason, the quality of the down, FP, and the structure of the sleeping bag are all important factors. For more detailed information on this topic, please see this article .
Of the three models, ISUKA and Montbell 800FP goose down, NANGA uses 770FP duck down. What we learned from this comparison is that ISUKA and Montbell leads to a difference in heat retention, while Montbell and NANGA appears to lead to a difference in heat retention.
We also tested the windproof and heat-retaining properties of the sleeping bag by sleeping inside it for about an hour outdoors in strong winds (maximum instantaneous wind speed of 13.0 m/s). Normally, you would be inside a tent and not be directly exposed to the wind, but we conducted this test as a field test
When you sleep on exposed snow, you can clearly see how easily the cold air passes through
As a result, the ISUKA offered excellent wind protection and warmth for the body, but the shallow hood meant that the head was exposed to a lot of cold air. In comparison, the Montbell had a deep hood that protected the head, kept the body warm, and was windproof, so I was able to withstand it for an hour without any problems. On the other hand, the NANGA allowed me to feel the cold all over my body, and after an hour my body became cold, making it far from comfortable.
weight
To ensure warmth, it is necessary to increase the amount of padding, and heat retention and weight are proportional. While it is best for mountaineering equipment to be compact and lightweight, achieving this balance is difficult for winter sleeping bags, which must maintain warmth. In terms of the three models reviewed here, I think all of them are quite lightweight considering their heat retention. Of these, the Montbell Alpine Down Hugger 800 #1 is noteworthy, weighing in at just 924g, which is below 1000g for its class.
Comfort
Of course, it's important to be warm inside your sleeping bag, but you also want to sleep comfortably. Looking at the materials used for the interior walls of the sleeping bags, the fabrics of ISUKA and NANGA were very soft and comfortable against the skin. Montbell felt a bit crisp and hard, and it also made the loudest noise when turning over. It wasn't to the point where it was difficult to sleep, but it bothered me. However, the stretchability was excellent, and even I, who sleeps in an awkward position, was able to sleep soundly.
The fit the ISUKA was excellent. While the other two models tighten around the neck with a drawcord, the ISUKA 's U-shaped shoulder warmers fit snugly, keeping the neck warm. Its unique 3D structure also conforms to the body, ensuring the entire body fits snugly into the sleeping bag, minimizing wasted space that can reduce warmth. Meanwhile the Montbell 's neck area feels slightly less comfortable than the other two.
Portability (storage)
NANGA is the most compact, Montbell . ISUKA is the largest While it has excellent heat retention, it does have to compromise on weight and size.
From left: ISUKA AIR 630EX, NANGA UDD BAG 630DX, mont-bell Alpine Down Hugger 800#1
On the other hand, packing a down sleeping bag can be surprisingly difficult, and depending on the item, it can require a great deal of effort. To reduce this burden, manufacturers have devised ingenious stuff sacks to accompany it. In this regard, Montbell 's stuff sack was exceptional. It uses the same spiral stretch system as sleeping bags, so the fabric stretches as you compress the sleeping bag, reducing the burden during storage. Another plus point is the wide opening. It also changes shape when packing; rolling it around stretches it out, elongates, and becomes slim. This is incredibly convenient, allowing it to fit perfectly into the dead space inside the backpack. The stuff sack also has two drawcords, making it extremely easy to compress. Models with two drawcords are indeed extremely convenient.
Functionality
First, let's talk about zippers. Honestly, each manufacturer has devised ways to prevent jamming, but there is no zipper that is completely jam-proof. The probability of jamming increases when closing the zipper from the inside with any model. Of the zippers, ISUKA had the least jamming frequency and was extremely smooth when opening and closing. Furthermore, NANGA zippers use phosphorescent resin, making them highly visible in the dark. This was a very useful feature.
Next, we looked at the water repellency of the surface. We conducted two tests to verify this
In one test, we continuously exposed the sleeping bag to shower water for 3, 5, and 10 minutes before evaluating the water repellency of the outer material and the penetration of water through the zipper. In the other test, we submerged the sleeping bag completely in a bathtub, soaking the down in water to see if it was still usable
We tested the product by showering it for a certain period of time to check whether it was watertight
The results showed that after three minutes of continuous showering, the NANGA jacket was damp overall, while the other two models did not allow water to penetrate the down until five minutes later. This water-repellent performance is truly impressive. In particular, the Montbell jacket showed some water penetration into the down after 10 minutes, but most of it was through the zipper, and the water-repellent properties of the outer fabric remained intact. You can have great confidence in the water-repellent properties of Polkatex, which boasts "the world's highest level of water repellency." None of the three models were able to prevent water from penetrating through the zipper. This may be an issue for the future.
Next, we submerged the sleeping bags in water stored in a bathtub. NANGA 's ultra-water-repellent down performance was outstanding. Even when submerged, the sleeping bag immediately floated up, making it difficult to submerge the entire bag. We repeated this several times, but the result was the same: the down never got soaked. The other two models sank completely into the water after about three minutes, becoming completely soaked.
If you just want to repel a little bit of water, the water-repellent fabrics from Montbell or ISUKA will likely work well enough, but if you're in a situation where humidity or moisture is chronic, then the UDD BAG 630DX seems like a safe bet.
summary
There were various evaluation criteria, but I think the main things people look for in a winter sleeping bag are heat retention and light weight. Through this test, I decided that if I were to use it on a 2000m-class winter mountain, I would go for the ISUKA AIR 630EX the Montbell Alpine Down Hugger 800#1 if I wanted something that would be able to withstand the cold but was also lightweight and portable . It would also be a good choice for people who prioritize cost performance.
On the other hand the NANGA UDD BAG 630DX showed that in terms of heat retention, the UDD BAG 810DX, which is one class higher, may be the equivalent of the two models compared here (or the AURORA light 600). While it depends on personal preference, we recommend this model for long mountain trips spanning several nights, with the temperature range mentioned above being a little stricter.
Finally, through this test, I was reminded that, although it goes without saying, when choosing a sleeping bag, heat retention performance is the most important thing. If a sleeping bag doesn't keep you warm, all other features are useless. After determining the temperature range that suits your needs, it's best to choose a bag while being mindful of the compromises and priorities you're willing to make, such as lightness, compactness, comfort, and other small features and parts. It's not a cheap purchase, so you want to choose carefully. I hope this test will be helpful when choosing your sleeping bag
We also recommend this article about sleeping bags.
- Warm your body from the core with the perfect sleeping bag (sleeping bag) - How to choose and 8 recommended items -
- How to choose a winter sleeping bag (sleeping bag) to make your winter tent comfortable and 8 recommended ones
- Comparison Review: Ultra-lightweight 3-season sleeping bag - A spectacular battle with a range of great items that are extremely light and warm -
- What to throw away and what to take? How to choose the best sleeping pad (mat) and 3 recommended pieces
TAC
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