Rab Ultrasphere 5 Sleep Mat Review

Backpackers talk all day about saving weight, but for me, saving space is just as important. Packs have a limited capacity, and the less the real estate takes of each item, the better. Next to the sleeping bag, my sleeping pad always took up a lot of space in my pack, that is, until I tried the Rab Ultrasphere 5.

This comfortable pad packs close to the size of a Nalgene, saving precious liters in my pack, and all with an industry-leading warmth-to-weight ratio.

Usually known for its jackets and gear, Rab has been making inroads into the backpacking market, dropping several new sleeping bags and pads in recent years. Ultrasphere 5 is the latest and most lightweight version, with new technology and design features that we had to try.

I tested this Rab pad on several camping, hiking, and backpacking trips in Illinois and Kentucky during the fall and spring. In many cases, temperatures have dropped below freezing, with local weather services even issuing frost warnings. This pad helped me (mostly) with everything.

In summary: The Rab Ultrasphere 5 ($255) reduces weight and space while still providing a comfortable pad. It’s not ideal for true cold-weather adventures, but in moderate spring and summer temperatures, it’s an adequate three-season sleeping pad. If you’re looking for a highly usable pad that won’t add any unnecessary ounces or take up too much space, the Rab Ultrasphere 5 is the ticket.

Compare the Rab Ultrasphere 5 to the options in our guide to the Best Backpacking Sleeping Pads.

Rab Ultrasphere 5 Sleep Mat Review

Design and features

Rab used two techniques to improve the pad-to-weight ratio. First, there are two layers of Thermo Ionic Lining Technology (TILT), the same foil-like fabric found in emergency clothing. It reflects your own heat back to you. Then there’s the unique pattern of offset air chambers, which Rab says helps trap heat.

The result is a 12-ounce, 3-inch–thick pad with a 5.5 R value, one of the best warmth-to-weight ratios on the market. GearJunkie’s top sleeping pad of 2025, the Therm-a-Rest NeoAir XLite NXT, has an R-value of 4.5 and weighs 13 ounces. NEMO’s Tensor Trail Ultralight has an R-value of 2.8 and weighs 13.9 ounces.

One of the few pads that beat this one Rab is the Exped 6.5R. That pad weighs 12 ounces and has an R value of 6.5.

Inflation and packaging

The Ultrasphere 5 comes with a standard inflating bag, but personally, I find those to be more work than they’re worth. Instead, I just blasted it the old fashioned way, and it worked fine. It takes me 3 minutes to fully charge.

I always appreciate the two-way valve on the pad. The valve was also low profile and flat enough that it wasn’t a problem when packing the pad.

In the past, I’ve praised Rab’s burrito-style bags for how easy it is to pack a pad. This one is a little trickier. The bag isn’t big enough to fit the pad. If you don’t roll the pad properly, it won’t fit.

I had to fold it in half straight up, blow all the air out, fold it in half again, and then fold it really tight to put it in the bag. On car camping trips, I found myself avoiding folding the pad, instead just stuffing it in my duffel bag. A bigger bag would have made things a lot easier.

That said, once you get the pad in the bag, it’s surprising how small it is. It’s 7.1 inches x 3.5 inches, about 3/4 the size of a Nalgene water bottle. I’ve downsized my pack in recent years, going from an Osprey Ariel 70 to a Gossamer Gear Mariposa 60. A few more liters means space is at a premium, so I’ll take (and enjoy) all the space savings I can get.

Comfort & Sleep

Like many other sleeping pads, the Ultrasphere 5 has a tapered shape, with a very wide point at the shoulders. This shape shaves off ounces and saves space. In some pads, I find that the mummy shape is too extreme, not enough room for my legs. This one was open enough, though, that I didn’t spill on it all the time.

As a combination of side and stomach sleepers, I never felt like I didn’t have enough room. I’m 5’6″, and the regular size was big enough. If you’re tall or need more space, there are wider and taller versions that cost an extra $20.

Unlike other pads, this one is incredibly quiet and wrinkle free. I’m a light sleeper and toss and turn, so I liked how little noise it made. I was worried that the confusion would feel weird to lie on (like there were big holes in my back), but I didn’t notice them. For me, this design is preferable to the long straight baffles that other pads use, which can put pressure on my spine.

Warm Question

Rab says this pad has an R-value of 5.5, which means it falls firmly into the three-season pad category. Although not suitable for severe winter conditions, this pad should provide adequate coverage during fall and spring nights.

Honestly, I wasn’t sure. I was colder than expected. I’ve slept on pads with low R values ​​during unexpected snow storms and didn’t feel the cold. When we camped in Kentucky in March, the temperatures dropped slightly below freezing several nights. Even with a Rab pad, 0-degree sleeping bag, and long underwear, I was cold. I added a sleeping bag liner and a hooded fleece, and that was still enough to keep me from shivering, and I’m usually warm.

If I had to choose a pad to take with me to high alpine areas or when hiking in unpredictable weather, I would choose a different one. After one too many freezing nights, I limit my use of the Rab pad to warm conditions only.

Strength

The last time I tested a Rab sleeping pad, the Rab Hypersphere Ultra 7.5, disaster struck. We broke through on a flat surface, and I couldn’t patch it up, which resulted in me having to sleep hard on the cold, hard surface. This time, luckily, Ultrasphere 5 and I didn’t suffer the same fate. Even with my dogs sitting on the pad, there was no visible damage.

The gray color of the pad means that stains are easily visible. After 3 days of climbing in Illinois without showering, my sweat, sunscreen, bug spray, and who knows what else left different stains on my face.

Price Note

The standard size Ultrasphere 5 costs $255. Compared to the best GJ sleeping pads, that price is high. Our top pick, the Therm-a-Rest NeoAir XLite NXT, costs $210. The Big Agnes Rapide SL, a high-performance pad I’ve reviewed in the past, costs $170.

Even NEMO’s top-of-the-line pad, the Tensor Extreme Conditions Ultralight, only costs $260 and has an R-value of 8.5, weighing 1 pound, 2 ounces. While the price of the Ultrasphere 5 is extremely affordable compared to the competition, it’s not really a budget pick.

Rab Ultrasphere 5 Sleeping Pad: Who It’s For

If the Rab Ultrasphere 5’s stated R value is true (which I’m not sure it is), the pad has the best warmth-to-weight ratio on the market. Even if it’s not as warm as it claims, the pad will still be a great spring and summer backpacking pad. After all, it weighs less than a pound, which is rare in the market. This pad will definitely appeal to hikers and ultra-lighters who count every ounce.

Considering it takes up about the same amount of space as a tallboy beer, it’s hard not to like how compact the pad is. If you can roll it with the necessary surgical-grade precision, you’ll never have to worry about finding room in your pocket for your puffy or extra fuel canister.

With ample sleeping space and a quiet profile, the Ultrasphere provides a comfortable place to sleep after a long day of hiking or riding. If you want to save space and the price tag doesn’t scare you, the Rab Ultrasphere 5 is a great choice for a backpacking trip.