Therm-a-rest Xtherm – What size?

I think that size would be perfect for you, being a side sleeper.

"I sleep mainly on my side and stomach …"

All the NeoAir pad are narrow when inflated, and narrower yet as the edges collapse.

IMHO the maximum functional width of a Medium or Regular is about 18" and tapers from there.

Definitely "try before you buy", or make sure you can return it no questions asked.

not so much for the length as width. The other two are only 20" wide, and as has been mentioned they're a little wonky at the edges. it is somehting like 6 ox. heavier than the one you're looking at, but if there's one area where I'm willing to carry extra weight it's the pad!

Have fun…

I am 5'9" and 167lbs and have a large and love it. The extra width is much more comfortable on my back, side, or stomach. The extra length is appreciated for two reasons, it ensures the pad doesn't slide down much since it is already at the foot of the shelter, and my pillow can move around and still be on the pad.

Extra weight I am more than happy to carry for the comfy sleep. I also replaced my quilts for the wide versions for the same reason – more comfort and virtually no drafts as I move around during the night changing positions.

Get the large size and cut it to length.

I haven't used the Xtherm, but have the Xlite, and I definitely found the regular too narrow. Even sleeping on your side, if you bend your legs almost at all, they'll be falling off the edges, and on your stomach your arms will probably just be on the ground. I'm quite slim, and even flat on my back, arms tucked close, my elbows were on the ground. The extra length is unnecessary so cutting that off makes sense.

How do you cut and inflatable to length?

There are several online videos on cutting and resealing inflatable pads. Basically, you determine the desired length, cut it, trim the inside baffles, and reseal using an iron. I have cut both the Neoair Xlite and Xtherm to length with good results.

"I haven't used the Xtherm, but have the Xlite, and I definitely found the regular too narrow. Even sleeping on your side, if you bend your legs almost at all, they'll be falling off the edges, and on your stomach your arms will probably just be on the ground. I'm quite slim, and even flat on my back, arms tucked close, my elbows were on the ground. The extra length is unnecessary so cutting that off makes sense."

What he said. I bought a reg. Xlite this season and am coming to realize I'd probably sleep better on a wider pad. I'm mostly a side sleeper.

Large. Having used/owned the xlite in both regular and large and the Xtherm in large, I would never go back to the regular. Too much comfort lost compared to the few grams saved. Not worth it. IMO ;-)

I own an XLarge XTherm and I had plans to lob off ~7" off the foot end. But then I thought about the lifetime warranty Thermarest offers and how that would be voided if I go Dr. Frankenstein. As a dedicated winter pad and at 1lb4oz it's still one of the lightest R5.6 pads available, with the added benefit of elbow room. As other have pointed out, and as I have complained recently in another thread, Thermarest measures their weight with the pad deflated. So my advertised 25" width is actually 23". And I can't see myself being comfortable on a 20" (read: 18") normal or medium size…. not with the edges slightly collapsing when I shift into side-sleep mode. If weight ever takes precedence over lifetime warranty I have 4-6oz to look forward to shaving.

I have an x-lite regular and x-therm large. For me personally, neither are comfortable. Size is not the issue – it's the horizontal bubble baffles that are just not comfortable for me.

I got the x-therm large after I got the x-lite, thinking that a bigger pad would solve the comfort issue – it did not. The horizontal baffles just push up in all the wrong spots. Plus, even with the large pad, if I get off center, I tend to "roll off" the x-therm if I get too close to the edge of the pad at night.

Compare that to the vertical baffles on the exped pads, which kind of cradle you and contain you within the pad.

For me personally, my old prolite plus or my exped UL MW pad, in combination with a gossamer gear thinlite pad (or ridge rest solar with a sled), is much more comfortable than the x-therm large. Plus, you can sit on the thinlite on the ground when you are resting during the day and not worry about leaks. Plus, if you do get a leak, and you have the thinlite, you are not totally SOL. There is not much of a weight penalty with that kind of combination vs the 20oz x-therm large, and the r-value is not bad.

I received the Therm-a-Rest NeoAir XTherm regular in the mail today. I know it falls off a bit at the side edges, but I can live with the width (measures 20"). I'm 5'11" so was wishing for another few inches in length. I was surprised to see they are conservative on the length measurement. It's supposed to be 72" but even after allowing for some falloff at the ends, it measures more like about 75" to me.

The photos are the ends of the Prolite regular (it really is 72") on top of the XTherm regular.