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Sea-to-Summit Ether Light XT Insulated Sleeping Pad Review

Sea-to-Summit Ether light XT Insulated Sleeping Pad review

The Sea-to-Summit Etherlight XT Insulated Sleeping Pad is a lightweight, inflatable sleeping pad that is 4″ thick and features air-sprung cells for maximum comfort, making it far more comfortable than Thermarest’s NeoAir sleeping pads and much quieter. Weighing 15 oz, it has the same durable three-way inflation valve and is easy to inflate by mouth or with the included pump sack. Sea-to-Summit pads are also rated with R-values, so you can objectively choose the correct amount of insulation to complement a sleeping bag or quilt-based sleep system.

Sea-to-Summit Etherlight XT Sleeping Pad

Ease of Inflation
Packed Size

Super Comfortable and Warm

Move over NeoAir, there's a new boss in town. This Etherlight XT has air-sprung cells which are way more comfortable, with a durable flat valve, and soft cover fabric.

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Specs at a Glance

  • Weight: 15 oz
  • R-value: 3.2
  • Type: Inflatable
  • Dimensions: 72″ x 21.5″ (25″ widths and 78″ long lengths, also available)
  • Thickness: 4″
  • Insulation: Reflective platinum layer and synthetic insulation
  • Antimicrobial treatment: Yes
  • Included insulation sack: Yes
  • Materials: 30d / 40d nylon

Sleeping Pad R-Value Minimums

If you sleep on the ground with a quilt or sleeping bag on backpacking or camping trips, you need to use a sleeping pad with an R-value between 3 and 4, if you want to experience the temperature rating of your quilt or sleeping bag. This may come as a surprise to many people, but it’s a well-established fact based on the existing EN sleeping bag temperature rating standard, and the new sleeping pad R-value standard, that will be rolling out to consumers in 2020. To learn more, see my article about the new Sleeping Pad R-value Standard. It also explains why so many people sleep colder than expected even though they purchase quilts or sleeping bags that are supposed to keep them warm at their designated temperature ratings.

The Ether Light XT Insulated Mat is a super comfortable sleeping pad

Comfort and Quiet

The sleeping surface of the Insulated Ether Light XT is made up of air-sprung cells, which mimic a pocket spring mattress so that the surface of the pad conforms to your body shape regardless of whether you sleep on your back or on your side. This helps keep you on the pad at night, without the need for extra side-rails to keep you from rolling off. These air-sprung cells are far more comfortable than the horizontally oriented surface of Therm-a-Rest’s NeoAir pads, which begin to feel like wooden boards if you sleep on them for more than a few nights in a row.

While the Insulated Ether Light XT is heavier than a NeoAir Xlite (R-Value 4.2) and has a lower R-Value than a NeoAir Xtherm (R-Value 6.9), it is 1.5″ thicker than the 2.5″ thick NeoAir pads and made with heavy-duty 30d/40d fabrics for increased durability. The added comfort of a thick pad and the air-sprung cells is so worth it, especially on multi-day trips when sleeping well is essential. The Ether Light is also insulated with synthetic fibers and not just a reflective layer, making a much quieter pad to sleep on.

Sleeping Pad R-Values and Air Temperature in Degrees

What’s the correlation between air temperature and sleeping pad R-values? When do you need a pad with a higher R-value? This table is based on Exped’s recommendations in Fahrenheit and Celsius degrees.

Air Temperature (F):503025100-15-25-40
Minimum R-Value12345678
Air Temperature (C):10-1-4-12-18-26-32-40
Minimum R-Value12345678

In addition:

  • R-values are additive, so you can combine two pads to increase your warmth level.
  • Women need higher R-values pads because they have lower body mass than men. An additional R-value of 1 is usually a good hedge for women and other cold sleepers
Flat valve closeup
The Ether Light XT has a flat three-way valve (twig not included)

Flat Valve and Pump Sack

The Ether Light pad comes with its own pump sack for ease of inflation. It mates to the pad’s flat valve, which is a three-way valve: one for inflating the pad, with an integrated nipple that lets you release air for more comfort, and a closed cap for closing the valve completely. If you lift both caps to deflate the pad, the air quickly rushes out of the big valve hole, so you don’t have to spend time evacuating the air or rolling up the pad multiple times to force it all out (like a NeoAir). Flat valves are also much more durable than stick valves since they don’t require a screw-type lock and roll up flat.

Pillow attachment system
The Pillow Lock attachment system ensures that your pillow stays attached to the pad all night

Pillow Attachment

I’ve never been one for backpacking pillows, but the Pillow-Lock attachment system that comes with the Ether Light XT has made me a convert.

The Ether Light XT comes with 4 velcro pads that you can stick to the top of the pad. These hold a Sea-to-Summit pillow in place so it doesn’t move off the pad at night. It works great. I was on a two-week trip this spring where I used this feature every night and it greatly enhanced my sleep experience and comfort. I used a 2.5 oz Sea-to-Summit Aeros Down Pillow, but the pillow-lock system works with any of the Sea-to-Summit’s inflatable pillows.

Comparable Sleeping Mats

Make / ModelR-ValueMin. WeightThickness
Sea-to-Summit Insulated Ether Light XT3.215 oz4.0"
Sea-to-Summit Comfort Light Insulated Mat3.721.8 oz2.5"
Therm-a-Rest NeoAir Uberlite2.38.8 oz2.5"
Therm-a-Rest NeoAir XLite4.212 oz2.5"
Therm-a-Rest NeoAir XLite Women's5.412 oz2.5"
Therm-a-Rest NeoAir XTherm6.915 oz2.5"
Exped Ultra 3R2.912.9 oz3.0"
Exped Ultra 5R4.820 oz3.0"
NEMO Tensor UL Insulated4.215 oz3.0"
NEMO Tensor UL Non-insulated2.513.8 oz3.0"


The Sea-to-Summit Insulated Ether Light XT air mattress is a super comfortable sleeping pad with air-spring cells that mimic a spring mattress. A full 4 inches thick, it conforms to your body shape and keeps yon the pad all night regardless of whether you’re a back or side sleeper. A flat valve and durable exterior fabric increase durability and reliability, while an R-value of 3.2 helps ensure that your sleep system will perform optimally at the temperature that it is rated for. Highly recommended!

Disclosure: Sea-to-Summit provided the author with a pad and pillow for this review.

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  1. I appreciate that they offer a 72″ x 25″ pad. Has anyone compared the women’s to men’s? It would be interesting to know how they truly differ.

  2. Great timing on the review. Was considering this or the revised Nemo Tensor while the REI member sale is still on, and I like the idea of the tougher fabric in the S2S mattress. Are there any other notable differences between them?

  3. Being old just got a little bit easier…

    • I just bought one for my wife and can confirm that the inflation sack works with the current Thermarest stick valves. It fits nicely into the inside of the bag’s nozzle.

      • langleybackcountry

        I do not understand how this would work. The shape of the valve is completely different and the S2S pump sack makes a positive connection sealing with the valve.

  4. Wished they offered a Regular Length in the Wide 25″ size. Only Nemo seems to offer this. I’m 5′ 6″ and find my arms laying on the cold ground using regular pads that are ~ 21″ wide. And I don’t need the extra 1′ length of the long pads which do offer the wider width. I know there are DIY approaches (scissors and iron) to take a Long/Wide and turn it into a regular length/wide but who wants to spend top dollar and have to modify it to make it right.

    • They do offer a reg wide pad at 72 in x 25 in

    • It looks like you can get the women’s in a sort of mummy shape st 72 x 25.

      • Thanks Cheri. That does look like a good size.

      • I bought the S2S Women’s Ultralight Insulated Air Sleeping Mat, size large (25”x72”) and like it. Even the paprika color! I’m male, 6’2”, 180 pounds. It’s a good length and width for me. S2S says it’s narrower at the shoulders than the “unisex model”. It is comfortable, quiet, and warm at least to the upper 40s, the temps I used it in April. And that pumpsack is great! I have to say I’m tempted by this Etherlight XT, but I’m a bit concerned that a 4” thickness will boost me too high in my tents and bivys.

    • And the women’s is on sale at REI for $157. I don’t know how the shape differs but may not be a bad idea to order it and find out.

  5. Unfortunately that free pillow code doesnt appear to be working.

  6. Any thoughts on how this compares to the Big Agnes AXL?

  7. Thanks, Philip for this review of the S2S Insulated Ethernet XT, it sounds like a good lightweight solution for UL backpackers who want some extra comfort like me. Can you describe the pad fabric surface? Is it a soft fabric feel suitable for using a comforter, like the new Nemo Tensor? And I’ve heard comments on other blogs that the pad surface feels like plastic and slips around on their tent floors,…..your thoughts, please?

    • Perfectly comfortable to sleep on. Thicker denier covering fabrics are like that. All pads slide on sil, PU or DCF floors. You get a small 1 oz piece of Gossamer Gear thinlight pad to put underneath that doubles as a sit pad. Well known UL hack.

  8. Just got one of these and spent a few nights on it. Really comfortable, more so than Thermarest. I think this will be a popular mat for those who don’t mind carrying a few more grams for a decent nights sleep.

  9. A few questions: Is a little patch kit included with this pad? Is the Exped Schnozzel inflation bag compatible with the valve on this (without needing any kind of adapter)? Is the “Pillow Lock” attachment a hook-and-loop system? If so, are the tabs on the pad hooks or loops? Aside from generally disliking hook-and-loop (wears out over time, ruins things like socks that accidentally get attached), i’m moving to a quilt for warmer weather and will be using it with a pad cover/sheet that i wouldn’t want to attach to the “Pillow Lock.” I guess i could just attach some little piece of the complementary fastener to the tabs to “deactivate” them.

  10. The pad comes with it’s own pump bag. Is there a reason you used a different one? Did you remove/cut out the one it came with?

  11. Hi Philip! Thanks for the review. It sounds like you really, really like this pad. Are you switching from the Thermarest NeoAir XLite to this pad for 3 season backpacking? Would the STS Etherlight XT pad be warm enough for you personally when coupled with your Thermarest ZLite Sol sleeping pad for winter backpacking and camping? Would you think the two pads (STS pad toether with the ZLite Sol) would be warm enough for someone who sleeps cold for winter camping?

  12. langleybackcountry

    I got this pad about a year ago and it changed my life. I was disappointed with the S2S Insulated Ultralight, and I have an old XTherm. They will probably just go into my backup/loaner bin. The S2S valve is the best, and the thickness as a side sleeper makes a huge difference.

  13. Another happy user here.

    I got interested in the pad when I read that leading reviewers in the UK were choosing it for personal use, plus the manager and half the staff at my local outdoor store.

    I’m a 5’10” male, but bought the large woman’s for the extra size and insulatation. The lozenge shape is great for side-sleepers – for the first time ever my knees aren’t hanging over the edge of my pad, and it makes a surprising difference to comfort and warmth. The width at the shoulders if fine for me, even though I’m quite stocky. Combined with edges that are far more supportive than other pads I’ve used, I’ve just spent a week without falling off the pad once and seven nights in a row where I had uninterrupted sleep all night. This is a first for me in half a century of wild camping – the most comfortable pad I’ve ever used, by some margin.

    My other priority is reliability. I’m very gentle on my sleeping gear, but I’ve had my fill of failed valves and blown welds. StoS say that they chose a more expensive and reliable welding technology than competing mats, and that the fabric was selected because it was the lightest that would hold a reliable weld. I had a chat and they are claiming that they haven’t had a single failed weld to date, which is impressive if true. Plus the valve looks robustly designed and repairable in the field using the spares in the patch kit, unlike the Exped valve…

    As a walker of “a certain age” I’m beginning to prioritise quality of sleep of weight, and the extra few grams are well worth it to me, as was the premium price. If it’s as durable as claimed, this is a best buy for anyone but the most obsessive gram-counter.

  14. Looks like a great mattress. I have a similar REI FLASH Insulated air mattress that uses a Sea to Summit valve and the compatible inflation/dry bag. It has a R 3.7 value which is “close enough” to the recommended R4.

    I’m concerned that my REI FLASH mattress may not be as durable as the StS Etherlite mattress. Field reports have not been good but REI says they will stand behind them IF it’s a manufacturing flaw, which most reported failures have been as welds failed.

  15. I recently purchased the rectangular wide version and instead of the claimed 19.4 oz mine weighed 21.5. This was for the mat only – no extras. I reached out to S2S and this was their response:

    “Generally, there are very few changes to a (Sea to Summit) product between pre-production and final production, but in the case of the Etherlight, some changes were made to the specification which increased the strength of the welds, and this led to the weight of the mat increasing.
    We are currently in the process of revising all of our sleeping mat packaging because of changes to the way R-Values are measured under the new ASTM standard. The R-Values and weights of all of our mats will be updated on both the website and on the next print run of packaging – but there will be a period when this change of listed R-Value will also cause confusion for the consumer. This was a topic which has been discussed at length with the heads of material testing at Therm-a-Rest and Exped – we are all intent on providing a transparent consumer experience.”

    I was also informed that under the new ASTM standard the etherlight xt will move from an r-value of 3.8 to 3.2. While I appreciate that the added weight increased the durability I’ll admit it was disappointing to see a 16% drop in thermal efficiency…especially considering this pad is so supremely comfortable. Maybe a lot of pads will drop under the new standard? I realize this was lengthy but for a pad of this price I thought people should know that they’re approx 10% heavier and 16% less insulating than advertised as of 10/18/19.

    Thank you for your many reviews and recommendations Philip. They are invaluable.

  16. It looks like somebody beat me to the punch but I was curious about the new ASTM standard rating as well so I reached out to see to summit and they corroborated the new value will be 3.2. That puts the X light, which is now listed at 4.2 using the same standard as a significantly warmer pad which weighs 12 ounces as opposed to the 16.1 ounces on my scale for the eitherlight XT-without the pump sack. Bummer.

    I will say that it’s comfortable and I love the fact it’s a tad bit wider, but I’m not sure that’s worth a quarter pounder, especially in light of TAR’s new valves.

  17. Hi Philip!
    Does repeated compression of sleeping pads with synthetic insulation (such as the STS Etherlight XT) damage that insulation and reduce warmth in the same way that it is claimed it does for synthetic insulation in jackets and pants?

    Also, do you happen to know when the new standardized R values for sleeping pads will be made available to customers?


    • I don’t think it does reduces the pad’s r-value in any substantive way, no.
      Standardized R-values will be made available to customers in the new year when REI has mandated it.
      Some are also already available from Thermarest on their new wing-lock pads.

  18. Hi. Just recieved this pad. But…it is really noisy. Am I missi g something…will the cracklu g sounds dissapear aftet some use?

  19. I grabbed one of the large mummy (78″ x 25″) at REI last year and used my 20% off coupon. Although it’s a bit big and heavy for my personal backpacking use, my wife can use it in place of a cot when we car camp. She even used it on an overnight backpacking trip we tried as a group in Big Bend a few months ago. We had to abort our two night trip when her shoe blew out but she managed well on it for the one night we got to spend on the mountain.

    I’ve used a NeoAir for several years and love that pad but I tried the Ether Light pad a night myself and it’s way more comfy to me than the NeoAir. I’m pondering the extra weight over my NeoAir. With my back problems, I also really like the 25″ width on the pad I bought. Of course, there are also 25″ width NeoAir pads but they don’t have that extra cushy 4″ thickness.

    The pump bag is self limiting on the amount of inflation. When it gets to a certain level, it just pops off the valve but the built in level is extremely comfy.

  20. I purchased one of these pads based on this review and I have to agree that this is the most comfortable pad (in the light weight category) that I’ve ever owned. Combined with an Aeros down lined pillow and its a slice of heaven for my tent.

    The stuff sack / inflation bag is just weird. The two are combined into one marginally functional unit. Because the stuff sack has two open ends it is not possible to put the repair parts (generously included) into the stuff sack and have them stay there. Because the stuff sack is small, and it becomes the opening for the inflation bag, it is hard to capture a full volume in the inflation bag so I’d say it took me twice as long and twice as many bags (partially full) to inflate.

    I intend to find another stuff sack, and to cut the little monster off the inflation bag so I can open it fully and capture a fully bag of air. Stitching the two together is a strange design, adds nothing to functionality and takes quite a bit of utility away.

    Other than that, thank for the review and recommendation. This article truly helped me make my selection.

    • When you use the pump sac, you blow into the small end at a distace of a foot or so. The resulting vortex pulls in outside air and fill that up easily .then you just hold the end vlosed and you squeeze the air into the pad…it is actually the best design of a pump sac i know of. Give it another shot!

  21. The S2S Etherlight XL looks good, & Philip has confirmed it is. Given the updated R-value of 3.2, & the R-value of CCFs (Sol/Switchback) of 2, that puts a cold weather R-value on the S2S + CCF at (3.2 + 2)=5.2. And it puts the weight (15 oz + 14ish oz) at 29 oz. (1 lb 13 oz). Given that, & the pack space req for a supplemental CCF, raised my question – has anyone tried the new Nemo Tensor Alpine? Looks similar in build quality & comfort to the S2S (maybe not quite as cush as 4″). It’s R-value is 4.8 & weighs 1 lb 8 oz.

    R value weight
    S2S Etherlight Insulated XL. 3.2 15 oz
    CCF 2.0 14 oz
    Nemo Tensor Alpine 4.8. 24 oz

    I hear the Alpine is super comfy & super warm. Thoughts?

    • Since my formatting didn’t work out – net/net is:

      S2S + CCF = 29 oz & a 5.2 R-value
      Alpine = 24 oz & a 4.8 R-value. (system packs smaller)

  22. Is the Sea to Summit Etherlight XT still your favorite pad.
    Did the product change since you last looked at it. I am asking because you reported it at 15 ounces but Sea to Summit states it is one lb and 1.3 ounces. Certainly not a deal breaker but curious

  23. I used my REI 20% discount last year on one of these. All they had in stock was the long wide version, which was heavier than I wanted but it is the ‘Grandma’s feather bed’ of sleeping pads. With my degenerative back condition, there have been times my NeoAire just wouldn’t handle my needs. Also, my wife can use it and get up off the ground from it. I may use this year’s 20% to grab the regular size. This is the most comfortable pad I’ve ever owned.

  24. Philip, I know you love the comfort of this pad & I take your word on that; however, shopping a pad for my wife I find many reviews agreeing with the comfort but stating how the lack of insulating properties makes it cold even into the 40’s. To the point I’m considering the new S2S Ether Light Extreme – it’s a load at 25 oz but the R value is 6.2, & likely similar comfort. Just how cold is the reg insulated in your experience? Our evening temps at higher elevations average 48 in mid summer. If she puts a CCF under her reg insulated S2S she’d be 2 inches higher then me on my Tensor. (The Extreme could also be my winter kit). Any thoughts given your time on that pad are appreciated.

    • I’ve taken my S2S down to 30 and it’s been fine. Why even botter with the extreme? Just throw a zlite or switch back under it. That way you also have something to sit on in winter while cooking and melting snow (you really do want an insulated pad to sit on). That will add 2 to the R-value of the inflatable pad and save you a lot of money. I trust R-value a lot more readers comments because I know how variable and often unreliable reader comments are on websites. You know they’re all syndicated across retailers, so everyone has the same reviews, and they never update them even if the product version changes. For example, you’ll have Altra Lone Peak 2.0 reviews mixed in with Altra Lone Peak 5.0 reviews even though they’re completely different products. It’s a total scam.

    • I decided to use last month’s Texas winter storm as a test bed for my camp bed. On a night that got down to 5°F, I could really the feel cold from below while using the Ether Light. I put a folding pad under it, which made it much better but still cool from below. I switched to my NeoAir and felt fine. The next night got to 0°F and the NeoAir kept me quite warm with a folding pad under it.

      A couple nights later was about 16°F and I again tried the Ether Light, this time without the folding pad. It felt about as cool to me at that temp as it did at 5°F with the folding pad. My personal feeling is the Ether Light will be comfortable for me down to 20-25°F. I think I likely sleep a bit warm, if that makes s difference.

  25. Good point, particularly about reviews. Thanks.

  26. I’m a 5’10” guy looking for comfort, and I’m using the “women’s large” version of this pad. It’s 25″ wide and 6′ long, so perfect for my needs. I’m not aware of a pad this cushy (thick) that’s any lighter than this one; the Big Agnes Q-Core SLX is probably the closest competitor? My pad weighs in at 23.5 oz, including the (2 oz) stuff sack. The sack doubles serves as an inflation sack and I think it works well, though some may prefer to leave it out. The pad is very comfortable, although the fabric feels a bit “plasticky” against your skin. I don’t find the pad to be noisy.

  27. Thank you for the great review, I’m finally looking at upgrading to a more comfortable pad and this is one I’m considering. I went to REI but unfortunately they didn’t have any in stock. I tried a Big Agnes Rapide SL Insulated Pad they had and it was very comfortable, but I cannot even find any reviews of it. Any experience or opinion about the Big Agnes Rapide SL vs the Sea-to-Summit Ether Light XT? I noticed the Big Agnes Rapide SL, or any Big Agnes, are on your Best 10 Sleeping Pads list. Thank you for any info.

    • Big agnes got out of the sleeping pad business about 5 years ago. That company has really stagnated during that time. So, I wanted to wait a year to see how well the Rapide stood up before listing it on a 10 best list, since I have an aversion to listing the latest bright shiny object. The S2S pads are bomber in my opinion and very innovative. Nothing comes close in my opinion.

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