Camping and backpacking sleeping pads have R-values that measure how much insulation they provide against the cold ground. Sleeping pads designed for cold weather use have high R-values while ones designed for warmer weather have low ones. This is illustrated in this table which shows the R-values recommended for different nighttime air temperatures.
|Air Temperature (F):||50||30||25||10||0||-15||-25||-40|
|Air Temperature (C):||10||-1||-4||-12||-18||-26||-32||-40|
If you only camp in temperatures above freezing, a sleeping pad with an R-value of 2 or 3 will be sufficient. But what happens if you buy a sleeping pad with a higher R-value for winter camping, like a Thermarest NeoAir XTherm which has an R-value of 6.9. Could you use it in warmer temperatures and without overheating and sweating all night?
To answer this question (originally posed by a reader), I reached out to my technical contacts at Thermarest because they have an elaborate in-house temperature testing facility for sleeping pads and sleeping bags. I knew they’d provide me with an answer based on data, not conjecture because they’re all engineering nerds. Got to love outdoor nerds.
I asked Brandon Bowers, who’s the category manager for sleeping pads, whether you could use an XTherm for camping in hot weather. He told me “Using a high r-value pad in summer is a strategy some people use so they can eliminate the need for multiple sleep pads. I would not recommend this if nighttime temps are above 75 degrees, but this is a personal preference.”
While there are bound to be individual differences with that threshold, it provides a good baseline to help minimize the amount of money you spend on sleeping pads if you plan to camp in summer and winter. Take me, for example: I avoid winter camping in temperatures below zero because it’s just no fun freezing your ass off outside below that when melting snow for drinking water, which can take a while. Zero degrees, no problem. But I’m over camping in really extreme cold.
If you’re like me and zero degrees is the coldest winter weather you want to gear up for, rather than buying a NeoAir XTherm (R=6.9), you’d be better off buying a Thermarest NeoAir XLite (R=4.2) for three-season use and stacking it with an inexpensive Thermarest Zlite Sol foam pad (R=2), for winter use (4.2+2=R6.2), since R-values are additive. You can even use an inflatable sleeping pad with an R=3 rating and a foam pad. You always want to carry a foam pad in winter anyway, so you have insulation to sit on while you’re cooking and melting snow or for an emergency.
In hot summer weather, you’ll probably be fine with the XLite up to nighttime temps of 85 degrees (F) or so. If you do combine the XLite and ZLite for winter, you wouldn’t have to buy an XTherm at all because it’s really only good for very cold weather use and not for summer temperatures.
I guess that is kind of a nerdy analysis. I’ll probably be selling my XTherm soon.SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.
I have used my Xtherm in summer with no overheating issues, but now I have more than one sleeping pad I find it is better to keep the more expensive Xtherm for cooler temperatures, and use the cheapest, lightest that I can get away with in the summer. The last thing I want to do is knacker a really expensive pad using it when I don’t need to. For summer I find a bit of 3mm closed cell foam coupled with something like a Klymit Inertia Xlite for a bit of upper body cushioning works best. I do use the CCF year round – not so much for the extra R-value it brings, but for anti-puncture, sitmat etc duties.
And one might argue that if night temps are 85 degrees you’re going to sweat your butt off no matter what the pad is. I know I would be!
Always good to get a scientific opinion to support or refute the conjecture.
Exactly. If it’s 85 at night, you’re going to be sweating your pants off. Inflatable pads do lose some R if you deflate them, so that might be a hack to get a bit more comfortable. I do that anyway because I hate sleeping on a board.
If the question is “can you?” you most certainly can. In my experience, I’ve never been “too warm” underneath. Regulation has always been done on top. I use an R8 in my truck during the summer without issue and no one changes their home mattress seasonally. An xtherm’s 1lb weight is still lighter than most other inflatables on the market with lower R values and is no bulk penalty. Of course, I’ve spent more $$ to save less weight so I guess I can’t throw stones.
We’ve had this raging debate before. I agree with you on all counts. I just wanted to get a different perspective from industry insiders with test equipment.
Did you really mean to say that X-therms are “really only good for very cold weather use and not for summer temperatures.” They are also great for moderately cold/cool nights, like between 30-60F, which can include much of spring and fall.
You’ve taken my words out of context. I said “If you do combine the XLite and ZLite for winter, you wouldn’t have to buy an XTherm at all because it’s really only good for very cold weather use and not for summer temperatures.”
I originally bought an XTherm for winter camping only. Given that an XLite, with or without a ZLite covers all seasons (as long as you don’t try to camp with them below about -10), the XTherm is redundant and heavier than a XLite by itself in Spring and Fall.
It’s recommended that people who sleep cold should add 10 degrees to their quilt or bag. Does this rule of thumb apply to sleep pads also?
The best solution if you’re a woman or smaller in stature or a cold sleeper is to get a woman’s sleeping bag or a women’s sleeping pad because you have less body mass than a man and generate less body heat. If you can only get a unisex sleeping bag, quilt or sleeping pad that hasn’t been tested against one of the industry standards for temperature ratings, adding 10 degrees is a decent hedge against being cold. You could ask why women’s specific quilts aren’t available but don’t get me started. If you look at the R-value for the women’s NeoAir XLite, it’s 5.4, which is significantly higher than the R=4.2 for the men’s version. It’s also available in shorter sizes and lighter weight which makes it popular with men who want a lighter weight pad.
I’m a cold sleeper and have used my Xtherm in all kinds of conditions – both warm and hot. But I primarily backpack in western Canada (BC), mostly in the mountains so nighttime temperatures are rarely above 15C/59F. I’ve had a few nights of coastal camping where the nights were close to 75F (about 22C) but it’s rare. I’ll be sticking with my Xtherm as my primary pad since I don’t want the extra bulk of layering pads in colder temps.
In layering sleeping pads to achieve the R value that you desire, does it matter as to whether the closed cell foam pad is placed above or below the inflatable pad?
I don’t think it really matters. But backpackers like to debate the topic.
Depending on the air pad it might feel warmer with the closed cell on top, at least initially, some pads feel cold for a few minutes, sometimes ice cold, but then they warm up and everything’s fine… until the dreaded 4:00 am pee break.
Closed cell warms up very quickly.
BUT keeping a closed cell on top of an air pad can turn into a wrestling match. You might require straps, 1/8 inch bungee cord, or (in a pinch) borrowed tent guy lines. If your quilt system already has straps there you go—strap them together.
It all depends on how slippery things are, how much you move around and how flat your camp is.
On Exped brand Mummy shape pads there isn’t any insulation in the two outer (shoulder to waist) chambers; so in that case closed cell on top totally stops the dreaded frozen elbow syndrome.
If you want to nerd out; calculate the r-value per inch and put the pad with the highest r/inch density on top.
Also remember that snow is warmer than ice (ie. a glacier) dirt is warmer than snow, and leaf cover is warmest of all. A nice flat snow platform with 2” of leaf debris on top covered by a ground cloth makes a very fine camp when both ingredients are available and you have a few extra minutes to prepare.
Would a Tensor Alpine and a closed cell foam pad such as a Nemo Switchback therefore be a good combination for the winter? Conversely , would my STS Etherlight XT insulated combined with the Switchback be sufficient for winter overnights 0-10 degrees?
Just add up the r values.
Of course, 5.2 so looks like I’m good. Now I can save money by not buying that new Xtherm XRT…
I have a klymit r valve 4, 4 season. So far its been good into the low 40s in the eastern USA.
My experience matches what others have said: I can be adequately comfortable at home with a think mattress, so I don’t think that it really matters. BUT…
The first time I took my Hennessy Hammock out with me on a car camping trip was in mid-July. It was *hot*. This was New Hampshire, so at night a cot with R-4 worth of pad was great. But in the mid-afternoon…aah. I did not have a thermometer, but if I did not find shade during a lunch stop I was dripping sweat. The hammock was located where it was in the shade and got a light breeze off of a pond. It was perfect. R-0 was what was called for. It was one of the few times that I have fallen asleep during the day while on a trip that was supposed to be for hiking.
Reading the comments I was just thinking, the best “pad” on a really hot night would be a hammock
I don’t believe it matters in warmer temperatures, only colder temperatures.
What’s the R value of your mattress at HOME? I can only guess it’s like R30?
We don’t change to a thinner mattress at HOME in the summer.
It’s just about how much weight you could save when backpacking.
The difference between an XTherm and an XLite is only like 5 ounces.
The XTherm is almost bulletproof. I’ve gone through 4 Big Agnes AXL’s.
The thinner you go on a pad, the more likely you’ll be sleeping on hard ground when it pops.
Thanks for posting this as a follow up to the R-Value pad summary a couple months ago. I am a cold sleeper and use a 20deg bag and a XLite for 3 season backpacking here in New England…sometimes the bag acts a quilt half off my body but my annual gear budget is finally happy and I sleep all night undisturbed with climate issues.
G’day – thanks for this. You are right on all counts and it was good to hear some technical advce instead of just opinion.
In the end though, i think the point is that sleeping comfort is very individual and personal. We all know this – and experience it with personal home choices for beding, including the differences on what is comfortable between gender, age, body size, and health.
And then there is what you get used to – in Australia we dont get the lows that you do in europe or usa and get more of the heat of, say, texas, but without the cold polar winters. So many of us are acclimatised to warmer temps, which means many of us wont mind a warm mattress.