I've read some forums, read posts on here and still not sure really how accurate the temperature ratings are on sleeping bags. I've got no reference having not used a sleeping bag for many years now.

For example, looking at this one: https://www.ultralightoutdoorgear.co...ing-bag-p11308

Looks great - says comfortable to -2 to -8 C and extreme to -25C.

I'm planning on wild camping, high up where temperatures might fall overnight to maybe -5C in summer/autumn, with a wind chill, so would this bag be appropriate ? Going from the basic specification I'd think yes, but would appreciate comment from people who have used a similar bag in similar situation.

Good question!

I did buy the Western Mountaineering Versalite 200cm this year. My girlfriend bought the same - and at this brand you can put both together (watch at buy for left/right). She is into climbing (high alpes (4k) / hiking and outdoor).

Wasnt so lucky to invest 550$ for the "not so often" usage. At this temp we dont often are out for hiking or overlanding, but can change now:

Komfort-Temperatur: -6 °C
Temperatur Limit: -13 °C
Temperatur Extrem: -30 °C
Size (innen): 165 cm / 180 cm / 200 cm
Packed size: 38 x 20 cm
Weight: 905 g

Did use it two times so far. It was warm inside with -5 degrees. It is high quality made and will be perfect for staying longer at minus degrees.

To sleep with two person in an xxl bag - was a cute experience.

Did read a lot of reviews and this looks for the best options. Quality is nice - therefore I didnt try another brand in this priceclass - I cant compare or give recommodations.

Important informations:

- Go near naked inside - this way it works better than with extended clothes.
- You get an XXL Size Bag for nontravel storage - to keep the goose down nice.

This need a lot more space for keep it at home. The small packed size is just for travelling. In my eyes an issue - for extended tripping by bike and everyday usage - independent what brand you take with you (goose down)?!

The 550$ still hurts personally - because it is a big investement for a 10 days a year usage. But it is one buy in a lifetime, I guess.

If you like to compare: https://www.westernmountaineering.co...ies/versalite/

Surfy

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About Overlanding, Travelogues, Equipment
Trans-Africa over the west coast

I'd guess the manufacturers must have some test method which they use to specify the temperature range of their bags but out in the wild conditions vary so much I've never been able to cross reference my experience with their numbers except in the most general way. I've camped in -15C in a down bag rated to -5C and been ok because the bag was dry and warm from being in a car all day. Conversely I've camped at -5C in a bag rated below -20C and had a miserable cold night because the bag was damp and wouldn't loft from being hauled across Europe on a bike for three wet days. Because I was chilled through I didn't generate enough heat to warm it up. Last weekend I was camping on the South Downs and used a really low end bag with a broken zip that my son found abandoned at a festival. It rained all night with a temperature around +5C (quite high up) and I was too hot in it - because I'd been running all day and my metabolic rate was up.

Based on the spec of the bag you gave the link to I'd estimate it would be warm down to about 0C, ok down to about -5C and you'd be miserable but wouldn't freeze to death down to around -20C. Everyone chucks these numbers about but camping in -10C is serious cold. I'd be carefully considering just about every element of my equipment if I was camping in that temperature, particularly if it was damp cold. My current cold weather bag - a Rab with twice the down fill of the one you're looking at is only just good enough for me to get a comfortable night at -10C. I can survive the night ok in colder conditions but that's not the same as being comfortable.

It's at this point Surfy and I must part ways: 'Go near naked inside'- not a chance in my camping world. Bare skin inside a cold nylon sleeping bag is something straight out of one of the circles of hell. You get to spend eternity enduring it as a way of paying for your misdemeanours in this life. And inmho it doesn't work. I don't even do it at home in the winter.

Also consider that sleeping bags are not a stand alone piece of equipment - they need to be used with insulating mats underneath them. A good mat can extend the temperature range downwards by quite a few degrees. Leave the mat out and heat will just soak strait into the ground.

My approach to this was to buy a good quality 3 seasons bag from Robens. In reality there is no "4 seasons" bag and if you are sleeping in very cold conditions you can always leave some layers of clothing on. Normally however I prefer to sleep in T shirt and underwear because anything I wear inside a sleeping bag tends to get sweaty, and it's not nice getting up in that.

I would echo what the guys say about an air mattress though. Not only will it insulate you from the cold ground, the improvement in comfort is an order of magnitude.

Temperature Rating of Sea to Summit Spark SpIII Down:

EN13537: 2012 Comfort: -2°C / 29°F
EN13537: 2012 Comfort Limit: -8°C / 18°F
EN13537: 2012 Extreme: -26°C / -15°F

Comfort — the temperature at which a standard female can expect to sleep comfortably in a relaxed position.

Lower Limit(Comfort) — the temperature at which a standard male can sleep for eight hours in a curled position without waking.

Extreme — the minimum temperature at which a standard female can remain for six hours without risk of death from hypothermia (though frostbite is still possible)
------

Think how you feel coldness is as personal and individual as your preferred sleeping position.
To sleep comfortable and warm my first attention goes the mats. Sleeping bag and mats have to function together to provide warm and relaxed sleep if you suffer sometimes from back problems like me. Last item I use in coldness is a merino wool cap.

I ignore the extreme rating. I would only look at this if I will go mountain climbing in high altitudes or too regions known for strong wind. For me just a value of safetyness for extreme conditions.

I want to sleep relaxed and I use the layer principle to avoid starting sweating. Sweating means getting awake and opening the sleeping bag to regulate your personal climate feeling. So not a relaxed sleep if you have to do this a couple of times in the night.

Normally I sleep in T-shirt and short underwear.
If it`s getting cold I use long merino underwear. If it`s getting more cold I add a pure silk inliner to this which adds 5°C to 8°C. This liner I use if it is too warm for the sleeping bag.
Will the temperature fall more down and I got awake through freezing I cover my sleeping bag with a rescue blanket(Polyester/Aluminium Foil).
If I know I could get cold I always carry 3 packs of rescue blankets with me because they small, lightweigt and you can use them as a reflection layer between mats and your sleeping bag too.

I tried out some sleeping bags/mats and I got a lot of product advices. Finally I think everybody has to find out yourself what works best. I change my gear as my needs change, this mostly more by age than by adventure driven.

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What's this swapping between men and women for temperature ratings? If there's a real difference (= ratings from experimental evidence) between men and women's experience in the same bag they should provide 'his n hers' ratings. If women do sleep warmer / colder in general it's not much help to me. Having said that, none of the rating on bags are that much help. I much to prefer to 'feel the cloth' as they say and make my own assessment.

How cold you can get in a bag without suffering some sort of consequence does seem to what the marketing people zero in on. It's as if the cold rating is some kind of macho statement where the better you buy the more it reflects on your status - "minus 20C, ha, you didn't buy one of those did you. They must have seen you coming. You'll freeze to death at festivals in that. Look at this one, this is what you should've got but I suppose budget was the problem. Rated -25C and stuffed full of the best quality goose down. Feel that quality; go on, feel it, rub it between your fingers, pat that padding, see how thick it is. That's what proper insulation feels like, not like those wafer thin cheap feathers shoved into your bag. Chicken's probably still running round somewhere looking for them".

What's never mentioned and rarely taken into account is how they cope in warm weather. Dump full length zips, build in a box foot and a mummy style head surround and you can get a few more degrees of cold rating for your marketing but it makes the bag almost unusable in warm weather. I'd much rather have a long zip so the bag can be opened out and used like a throwover when it's warm. The zip might make for a cold spot at the bag's limits but I'll trade that happily for some warm weather versatility. For the last couple of long bike trips we've dumped sleeping bags altogether and used domestic down filled duvets. A couple of them came secondhand from places like Craigslist and cost next to nothing.

This has mainly to do with the lower metabolic rate and lower muscle ratio of women.

The body heats itself through biochemical activities called metabolism.
Non active muscles add ca. 20% to body temperature. If you are getting active with muscles work e.g. sport than muscles work produces heat up to 2KW. That`s the reason why you start sweating when you do a hard workout.

Around 15% of body heat is produced by the brain. Why the brain is hidden in the bone box called skull and isolation tissue like fat oder muscle tissue is missing you will start automatically wearing a cap when you feel loosing heat.

If the body temperature gets too warm, heat must be evaporated to secure the metabolism function. 90% of produced body heat will evaporate over the skin because it is the organ with the biggest surface(~2sqm). 10% of heat will be evaporated through breathing. Women who have generally a lower metabolism rate evaporate less heat over the skin which is the reason why they faster get cold compared to men. If they evaporate less heat over the skin, they need a warmer sleeping bag.

Women normally also have a lower muscles ratio than men. In relation to body weight women have a muscles mass of 25 -35%. Men do have 40 - 50%.

When you sleep your muscles aren`t active but the metabolism is still supplying energy in form of oxygen, glucose, fat and protein to them to keep them ready and in shape for suddenly actions (leftover from our evolution and the reason why we loose body weight if we are undersaturated with calories and why we gain fat/muscles if we are oversaturated with calories during sleeping ).

The difference of the muscle/body weight ratio and the lower metabolism is the reason why women feel faster cold. Think every men knows this in form of discussions to heat up the room or by cold feet in bed...

And it`s the reason why women`s temperature feeling is taken to norm sleeping bags.

Fair deal I think.

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Yes, I'm pretty familiar with metabolism. A biochemistry degree + seven years in a research lab gave me a reasonable grounding in the theory, and running (another) ultramarathon last weekend made me very aware of how it works in practice.

My comment about men and women was more one about how the brochure / web site (or wherever the quote came from) seemingly cherry picks the information that shows their product in its best light. I wouldn't be surprised if the next version shoves a pig inside the bag and uses whatever temperature it feels comfortable at in their advertising: "a great night's sleep at -40C say our test porkers; and it protects down to liquid nitrogen temperatures so it should easily be good enough for any nuclear winter our politicians generate while trying to fix global warming. Buy now - 20% off stock clearance offer."

Couldn`t know that you are professional but thought maybe someone didn`t know....
My RESPECT for ultramarathoning

As an online vendor you have to decide which kind of details you offer to convert interest into an easy sale.

Being in sales all my life means being in direct contact with critical thinking buyers and at once delivering satisfying answers to every kind of stupid and intelligent questions. By this I can tell you that intellignet questions got less and less over the years.

Meanwhile a lot of buyers are only interested in customer reviews and often these are the effective arguments to drive a sale. These type of buyers is steadly growing, they ask more on facebook or on amazon than in forum or to the manufacturer/distrbutor.

Sorry but as ignorant the buyer group grows as easy it is to sell bullshit with nice buzz words and funky graphics. Makes me earning money much easier...So with your words pigs could have a potential in future to be a real sales argument...

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The phrase 'pig in a poke' is what I had in mind.

I guess 'honest, decent and truthful' is laughably simplistic in todays sales environment. One step ahead of the police is probably closer to it.

I've been buying and using cold-weather sleeping bags since the seventies--before that, too, if you include those gigantic, kapok-filled monstrosities so common before the advent of modern synthetics. That being the case, I can report that you couldn't really trust temperature ratings back then, either. Many companies rated their bags for survival (i.e., you probably won't die during the night at this temperature) but described their ratings as if for comfort.

More reliable ratings could be guessed-at based on measurements of actual loft--same as today, although the manufacturers were apparently very good at fluffing and plumping to achieve maximum measurable loft without much bearing on what happened during actual usage. I note that the link given by the OP doesn't seem to offer loft measurements, and this alone would rule out a sight-unseen purchase in my book. 50 years ago, as today, the buyer had to draw their own conclusions based on whatever scanty data was provided--and tune out the sales staff unless by chance in the presence of one who was both experienced and honest.

I've always discounted temperature ratings by at least 20 degrees F, often more. I've discounted further to allow for damp insulation when appropriate, and further still if not planning to use a tent--a small tent is worth 10 or 15 degrees, a larger tent somewhat less. Then I try to allow for general states of exhaustion or inadequate blood sugar, either of which makes me sleep much colder. My resistance to cold (or ability to generate warmth) has deteriorated as I've gotten older, too. In all respects, YMMV.

Mark

Hello

The bag in your link says -2°C to -8°C testet by EN13537.

What that exactly means -> google it.
Extreme is useless, don't know why they use that.
But someone who will camp at -25°C already knows that.

All those ratings are without wind, in a tent, so if you camp without a tent you have to look at the top layer of the fabric or use a additional bag for windcover.
It gives you a rough idea when comparing different bags.

Outside of Europe EN13537 is not used. Then it depends on the reliability of the manufacturer what is used.

You also can compare bags by the ammount of down used.
But be carefull, a large and wide bag needs more filling than a small bag for the same insulation.
Then the quality of the down matters a lot.
The bag in your link says "430g of 850+ Fill Power"
https://seatosummit.com/product/spark-spiii/ ->specifications
the specs are similar to
https://www.westernmountaineering.co...ies/ultralite/
where they say -7°C, with a bit less inside girth, so more down in the wall of the bag ->loft.

The r-value of the mat is as important as the bag itself.

So much for the theorie/physics, a lot of personal factores come in on how nice your sleep will be.
Empty stomach, hat, (stomach, side or back) sleeper, etc.

Go to a good shop with a sales person who knows the stuff and buy there.


sushi

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My RTW:
http://www.youtube.com/user/MrXt660ztenere

Reminds me of an aircraft mechanic I once met, he was changing a bearing which had been dunked in liquid nitrogen to shrink it. The company provided heavily insulated gloves to handle it, but he evidently thought they would be OK to use to pick the bearing up out of the liquid. Of course the liquid soaked straight into the glove....

Thanks for the discussion, so it's exactly what I thought, just a number to rate one against another and doesn't actually tell me anything useful unless I have extensive experience of at least one sleeping bag already rated against that standard.

So for my first bag I need to just buy one and see how it goes, based on the advice of a shop assistant and some YouTube reviews

May as well ask "what's the best tent/oil/helmet/travel bike"

There are plenty of review sites around though - do a few searches for "best 3 seasons sleeping bag" or whatever. By the time you've read through a bunch of those you should have a fair idea of what brands and models fit your bill. In my case I was surprised to find fit came into it as well - the first one I got was way too tight round the shoulders, so being able to try them on in the shop is a plus.