Temperature ratings on sleeping bags. US vs EU

American bag ratings are done basically like this

1) Would any one beleive it if we said it warm down to X temperature?
2) If the answer is yes, proceed to step 3. If the answer is no, return to step one and make up a new, higher number.
3) Put it in a package and ship it.

At least, thats what it feels like sometimes.
I find it difficult to impossible to trust bag ratings unless I have tested the bags myself. Regardless of what standard is used to rate the bags.

Technically, the American rating should be what warmth level the average sleeper will remain comfortable at. If the bag is rated for 32F/0C deg, then some people might boil, some might freeze, but the *average* person should be comfortable at 32F/0C deg.

I know nothing about European temp ratings but here in the US, be very careful about temp rating exaggerations!

Most major brands here in the US overstate the warmth and understate the weight of their bags! Sure, warmth is both subjective and dependant on a wide range of factors; however, it is also true that far more people complain that their bags perform more poorly than rated — then the other way around. Marmot is generally guilty on both counts (warmth and weight ratings) — but this is not to single out Marmot, as most other brands aren't honest either.

Sadly, it seems like most honest gearmakers here in the US are the smaller players: MontBell and Feathered Friends come to mind.

Western Mountaineering has a reputation of going the other way — their warmth ratings are generally conservative — meaning your bag may actually be warmer than rated!

Don't forget, MontBell is Japanese.

In my experience the Marmot bag ratings seem consistently off the mark. I own three of their bags. I love the bags, esp the Atom, but they don't go down as far as they say. I think a lot has to do with the "sewn through" design the bags I own have versus a fully baffled design.

I have a Western Mountaineering bag (fully baffled) and it's temp ratings are right on if not a little conservative.

So in order to stay warm, buy a heavier and warmer bag than what the rating might imply?

The EU-rating isn't too perfect either. A person living in Greece will freeze at a higher temp than a person living north of the Arctic circle, but the EU standard is used by all manufacturers in Europe. The result is that most of the bags sold in Norway had to change their ratings. My -25C winter bag was suddenly only -17C… Still keeps me warm though :-)

Thanks for your replies!

Helge:

I think it's great that the EU has a uniform standard. Perfect or not, it allows for comparison across the board. In case you don't already know, there is NO uniform standard here in the US at all. And should anyone try to push for one, I'm pretty sure many of the bag manufacturers themselves will protest the loudest!

Separately, yes, you can buy a heavier bag to allow for manufacturer "optimism". A second option is to save some weight and bulk by selecting your bag with the intention of wearing your warm jacket/pants/socks in colder nights.

The EU Extreme rating is something I don't think should exist! It purports to be the temperature at which you'll feel very cold but won't die – in other words, way beyond the parameters of the bag. Some companies are only quoting the extreme rating, without explaining what it is. Any potential buyer would of course assume that the bag would be warm at that temperature.

The number of variables does make rating bags hard. Some people sleep warm, some cold. The type of shelter and insulating mat, the humidity, the wind, whether you've eaten recently, whether you are warm when you get into the bag, whether you are wearing damp clothes – all these can affect how warm you'll feel.

That said, ratings can be used comparatively. There isn't that much difference in sleeping bag design. I'd be suspicious of bags rated much lower than similar bags with the same type of fill.

This bag, unlike most sold in the US, is correctly rated for a male's lower comfort at 30F or -.6C. You can trust the EN 13537 test procedure rating if you use an equivalent R value pad to what they used to test the bag.

The EN13537 test uses the original Thermarest Standard self inflatable pad, which is no longer manufactured. It is 1.75" thick, un-cored open cell foam, with an R value of 5.8.

If you sleep on your back, then approximately 35% of the bag's warmth is derived by the R value of the compressed bag insulation plus the mattress. If you sleep on your side, it is about 18%. If you sleep on your stomach, it is about 50%.

Helge,
I do not own the bag you are considering. But I do own 5 bags of various ratings.
What I suggest you do (and what I've done in the past) is compare the grams(oz) of down in the bag you want, to the weight of down in Western Mountaineering bags (or MontBell). These are consistently mentioned as 'fairly' rated by posters here.
Also, If you can actually look at a bag, measure its loft, and compare that again, to reputable bag manufacturers.
I actually compared down density in grams per square meter of bag surface area, then added a fudge factor for differences in fill power. (such as the ratio of those two numbers)

Richard:

The Marmot Hydrogen is quoted simply as 30F in the US (-1C).

I am trying to decipher the EN13537 chart you pasted above.

4.5C (40F) is the low end of comfort temp for women.
What is it for men?

-0.6C (31F) is the low end of "adaptive" temp for men.
What is it for women?

Finally, the above illustrates what I meant above by gearmakers' temp. rating "optimism". To me, it is exceedingly DECEPTIVE to advertise 30F for a bag when the gear maker knows full well that applies to an experienced user who knows to wear appropriate clothing in order to adapt!

This from the European Outdoor Group (http://www.europeanoutdoorgroup.com/):

The EN 13357 temperature tests use a thermal manikin which is a full size humanoid dummy with heaters and temperature sensors. The manikin is placed inside the sleeping bag and both are placed in a climate chamber. The manikin is heated to simulated body warmth. The air temperature is measured in the climate chamber and on the skin surface of the manikin. From these measurements, the insulation value of the complete sleeping bag is calculated.

The temperature recommendations are defined by EN 13537 based on the measured insulation.
EN13537 produces four temperature results – upper limit, comfort, lower limit and extreme. These give ratings for a standard man weighing 80kg and for a standard woman weighing 60kg.

• The EN 13537 Upper Limit or Maximum Temperature is the highest temperature at which a ‘standard’ adult male is able to have a comfortable night’s sleep without excess sweating.

• The EN 13537 Comfort rating is based on a ‘standard’ woman having a comfortable night’s sleep.

• The EN 13537 Lower Limit is based on the lowest temperature at which as ‘standard’ adult male is deemed to be able to have a comfortable night’s sleep.

• The EN13537 Extreme rating is a survival only rating for a ‘standard’ adult woman. “In the risk range a strong sensation of cold has to be expected and there is a risk of health damage due to hypothermia.” This is an extreme survival rating only and it is not advisable for consumers to rely on this rating for general use. The best guideline temperatures for purchase decisions are the TComfort and TLimit ratings.

In the Marmot example given the 0.6 Lower Limit and Marmot's -1 are pretty close.

Helge:
You have been given some pretty good advice above but in the final analysis much will depend on your metabolism and the conditions in which you find yourself on any given hike. Perhaps by searching this site for reviews of various bag manufacturers you will be able to identify those manufacturers who are consistently rated by active users as being accurate in their ratings. I certainly can testify to MontBell being accurately temp rated and of very high quality. MB bags are also exceptionally light and compressible. Western Mountaineering is another bag manufacturer that carries a great rep and and whose temp rating are accurate if not conservative.

If you do not want to create a sleep system that includes the bag, pad and clothing combinations, then an old piece of advice that still merits repeating may be helpful: Buy a bag that is rated 10 degrees below the coldest temps you are likely to encounter.

Chris:

At first glance, -.6C and 31F may seem the same, and indeed, the two numbers are very close. But that's not my point.

Presumably because of EU regulations, Marmot discloses much more information to European consumers — such as 40F is deemed the lower end of comfort zone and 31F is the lower end of "adaptive" zone.

Here in the US, Marmot displays only one number, with no explanations, caveats whatsoever! Now, if I buy a bag and the maker rates it a straight 30F without any explanations — then I would assume that this bag will be OK for an average sleeper at that temp. The problem, however, is that Marmot chooses NOT to disclose to the American consumer that 30F is really the LOWER END for even an experienced user who knows to be adaptive and wears "appropriate" clothing!!! Now, THAT'S DECEPTION!

In contrast, MontBell users (such as myself) and Western Mountaineering users generally agree that their bags are good to the rated temps — in and of themselves — without need for adaptive experience and appropriate clothing!

Helge

Whilst I cannot provide a direct comparison with EU ratings, I have used a Nunatak "Arc Alpinist" on 2 trips to Norway. The quilt has 11 oz (311 gm) of 800+ down fill. I have been more than comfortable in both a tent and a bivvy at these times of the year in Rondane NP. So perhaps you should look at the quality and amount of downfill. Of course YMMV (YKmMV)

Roger

Benjamin, that's a good point. Marmot don't have to have their bags tested under the EU regulations, nor do they have to display them. I've just checked the Marmot Europe web site (http://www.marmot.de) and only a single temperature rating is quoted, as in the US. It does seem odd that when the EU figures are available Marmot doesn't quote them. I've tested 5 different Marmot bags over the last five years and have found all of them warm enough as rated (most tests before the EU regulations came in) but I am a warm sleeper. I too have found Western Mountaineering bags excellent. I've never used Mont-Bell bags but will be doing so very soon.

You also tend to see more exaggeration of the grade of the down in the US compared to the EU.

OK, this thread is getting depressing. :)

I like the idea someone offered of normalizing sleeping bag ratings. We can look at a manufacturer most people trust and the weight of the insulation they use to get a certain rating. Then we can look at how this sizes up with other vendors. One would have to compare apples to apples, as it were, since different manufactures make bags differently. The most notable is "sewn through" versus "continuous baffles" but I suspect that tightness of fit might be a factor as well. Still, it would be a good place to start. Thanks to whomever posted that. I never thought to give this a try.

Why can't BPL take the initiative here. There is some credibility here that could highlight better manufacturers products while giving a believable arms length evaluation.

Just a thought.

MikeB

Thanks for all tips!

If I had looked a bit closer I would have found the EU-ratings for the Marmot bags on the European site myself. Can't see how I missed it… Thanks Richard!

I find that the lower comfort rating in the EU standard fits me pretty well. I'm a warm sleeper, and with a silk liner in the bag I'm pretty comfortable without wearing more than a boxer at temps around the comfort rating. The silk liner is also a great way to keep the bag clean when on hikes for several weeks.

What I was worried about was that the temperature ratings given on American bags were closer to the EU extreme temp than the comfort temp.

H.

..just to add a little more info. Here are the EN test results for Snugpaks; provided by a company rep. I own three of them, and they seem a few degrees C colder than rated, as confirmed by the EN tests. My Montbells are right on, but I can't find test results for them.

I learned from Jardine's book and these forums and a bit of logic thinking in hindsight that it is all about loft. Allthough two differntly made sleeping bags with the same fillWEIGHT should almost have the same warmth (some differences will occur due to different design features), their weights may vary due other materials used. What we all want is the leightest sleepingbag that will be the warmest.

Would a ratio of loft over total weight of bag give a good figure for comparing sleepingbags?

Two hypothetical SB's: the first having 3" of loft weighing 50 oz would give a rating of 0.06, the second having the same 3" of loft weighing 40 oz would give a rating of 0.075. Both SB's have the same loft, hence the same warmth, but the second has a higher rating and so would be better. This would even make it easy comparing a downbag vs a synth.bag. In my example the first one could be synthetic, while the second one could be down.

For ease of numbers i'd multipliy by 100 giving one SB a rating of 6, the other a rating of 7,5.

Would this work?

Eins

Eins:

I like your ratio. It is objective and it takes into account the relationship between warmth (loft) and weight.

There are too many variables for that to be reliable. It would probably work best for down products, but fill weight is harder to manipulate than loft measurements. Synthetic bags can hardly be measured by loft for accurate temp ratings. Some insulations provide more insulation per loft inch and per ounce of insulation than others. clo/oz measurements seem to be the most important warmth measurement for synth. insulations: http://www.thru-hiker.com/anyboard/forum1/posts/8773.html

Jardine's information in his book is innacurate. It was the best he could come up with at the time, but has since been made obsolete. I would love to see a measure of what clo values are need to meet european standards for different temperature ratings for my own bag making purposes (Richard?, BPL?)