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Therm-a-Rest MondoKing 3D Review

Our favorite option if you need a narrower comfy pad.
Therm-a-Rest MondoKing 3D
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Price:  $180 List | Check Price at Amazon
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Pros:  Warm, comfortable, fits in a smaller tent
Cons:  Heavy
Manufacturer:   Therm-a-rest
By Maggie Brandenburg ⋅ Senior Review Editor  ⋅  Apr 25, 2017
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#3 of 15
  • Comfort - 40% 9
  • Ease of Use - 20% 7
  • Warmth - 20% 10
  • Versatility - 10% 7
  • Packed Size - 10% 6

Our Verdict

The Therm-a-Rest MondoKing 3D Large is our Top Performer for Comfort and Size. It is a large, self-inflating mattress that rates super highly when it comes to comfort and warmth. Featuring four plush inches of cushy foam, this mattress does a stellar job insulating you from the cold ground while supporting your pressure points and making you wish your bed at home was this nice. While costing around $180, this camping mattress isn't the cheapest but is also far from the most expensive mattress we reviewed. Though it doesn't pack down as small as some other camping mattresses, its astonishing comfort and tent-friendly width make it highly competitive with our Editor's Choice Award-winning REI Co-op Camp Dreamer XL and an excellent choice for a weekend at a music festival or a family reunion in the woods. If you're looking to pair intense comfort with smart inflated dimensions, this is the camping mattress for you. We are stoked to recognize the MondoKing as a Top Performer.

Compare to Similar Products

Our Analysis and Test Results

When we set out to review camping mattresses, we knew it would be challenging to tease out how they stacked up next to each other (pun intended). In order to find out, we put these mattresses through a myriad of tests. While the MondoKing 3D performed better than all the other camping mattresses in this review, it couldn't quite beat the MegaMat and REI Co-op Camp Dreamer, and here's why…

Performance Comparison


Compared to your standard inflatable sleeping pad or basic air mattress, using the Therm-a-Rest MondoKing 3D Large is bonafide luxury camping. Featuring vertical side walls means that you can utilize the entire 25 inch width and 77 inch length to spread out and sleep like a king among starfish. If you're feeling like you need an even larger sleeping space, the Therm-a-Rest MondoKing 3D also comes in size XXL, which is 30 inches wide and 80 inches long — more similar to the surface area of many of the other camping mattresses in this review, including the Exped MegaMat, Therm-a-Rest NeoAir Dream, and REI Camp Bed 3.5. So while it's always great to have options, read on to learn why we think the MondoKing 3D in Large might be a better size for your life.
The MondoKing boasts an impressive four inch foam core, giving you the same thickness of comfortable goodness as the Exped MegaMat 10, and can be adjusted in firmness with a few breaths pushed in or let out. This flexibility allows the MondoKing 3D to accommodate all kinds of sleepers, whether you've got back pain, you're a side or stomach sleeper or even if you sleep with your 70lb dog. However, our reviewers found that this mattress was challenging to deflate to your comfort level simply by lying on it with one of the two-way valves open. The air-filled foam inside was so rigid that we had to actually get up and fold down the end to let out as much air as we wanted to make it fit our comfort needs. While this wasn't our ideal way of adjusting the air level in a mattress, it seemed a minor inconvenience when compared to the comfort and support of the MondoKing.

The soft polyester surface of this mattress provides a non-slippery, non-plastic-y plane that you can comfortably lay your cheek on without worry of sticking uncomfortably in warm weather. While we found this mattress to be far more comfortable than just about any of the other camping mattresses we tested, we also discovered that it lacks the conforming, memory foam-like feel of the Exped MegaMat. Overall, we rate the MondoKing 3D a 9 out of 10 for comfort.

Ease of Use

We had heard that the MondoKing 3D takes a REALLY long time to inflate the first time you get it out of the shrink wrap it comes in, and we found that to definitely be true. Our reviewers were able to speed up the initial inflation a bit by adding periodic breaths over the course of several hours, but we would definitely not recommend taking this product out into the field without first having fully inflated it at home at least once.

After the initial inflation, we were impressed with how quickly this self-inflating mattress goes from stored in its stuff sack to fully inflated and ready to cradle you to sleep. Though this mattress does not come with a pump, our reviewers never found themselves wishing they had one — the two two-way valves are designed and located so that you can easily get them to your mouth and bite them to add a couple quick breaths, and the impressive self-inflating capacity of the MondoKing means you don't have to huff and puff to top this mattress off. Within five minutes of starting the inflation process, the MondoKing was ready to soothe us into dreamland.

The MondoKing 3D comes with easy-to-follow deflation instructions that help make the most of having two valves for deflation. However being full of foam, the MondoKing requires a significant amount of body weight to really squeeze all that air out — there's a definite method to the madness of getting this mattress back into its storage sack. By following the directions included with the MondoKing, and using our entire body weight (plus a little extra bouncing!) we were able to fit it back in its bag relatively easily. The MondoKing is a little bit more challenging to roll down tightly if you forget that the two-way valves mean you have to close them between rolling iterations to prevent the mattress from inflating again.

So overall we found the MondoKing to be incredibly easy in inflate, rather specific to deflate and fit back in its bag, and the bag very convenient to carry and store. When compared to the Exped MegaMat, our tests revealed each to have different strengths and weaknesses, which we concluded makes them equally easy to use. We give the MondoKing 3D a 7 out of 10 for ease of use.


The R-value says it all when it comes to the warmth of the MondoKing 3D. R-value tells you the insulating power of any given sleeping pad or camping mattress, giving you an idea of how cold of a surface you could comfortably sleep on without that coldness seeping through to your body. To winter camp, it's generally recommended that you use a sleeping pad or mattress with an R-value of at least 4. Coming in with an astonishing R value of 11.4, the MondoKing is well-equipped to insulate you from the frozen ground and maybe even from an iceberg! It's also just as important to note that unlike the cold-temperature rating of a sleeping bag, having a camping mattress with an R-value this high won't make you pour sweat in hot weather. This is a solid four-season camping mattress, which we give a 10 out of 10 for warmth.


Based on the overall size and weight of the MondoKing 3D, this isn't the camping pad you would take on a backpacking trip. You're not going to want to carry this mattress too far from your car or garage. However, as a full 5 inches narrower than most of its competitors, the MondoKing has a few advantages. Remember toward the beginning, when we promised to tell you why we think the MondoKing 3D Large might be a more convenient size for your life than the MondoKing 3D XXL? Well here's why.

Your average two-person tent is around 50-55 inches wide. This means that if you're using a 30-inch wide camping pad like the MondoKing 3D XXL, the Exped MegaMat, or the REI Camp Bed 3.5, you can only fit ONE camping pad into your TWO person tent. However, by using the well-performing MondoKing 3D Large, you can fit TWO of them side-by-side inside a two-person tent, like the tent rating suggests. While we suggest you check this against your own personal tent width, as tent styles and sizes may vary, you're much more likely to be able to fit the promised number of people in your tent by using the MondoKing 3D Large than most of its competitors from this review. For this reason, we not only rated the MondoKing 3D a 7 out of 10 for versatility, we also awarded it our Top Performer for Comfort and Size.

Packed Size

When packing the car for a weekend of camping, the MondoKing isn't too large to leave behind, and more than makes up for its size with its comfort. While we wouldn't be stoked to pile seven of them in the back of the van, the space it takes up is pretty comparable to the other highly comfort-rated mattresses in this review, such as the Therm-a-Rest Luxury Map and the REI Camp Bed 3.5. And while the internet lead us to believe that we could pack this mattress back down into a nice little 7 inch by 26 inch package, we found that very challenging to achieve. In reality, we found that the MondoKing fills its storage bag, making it almost the same size as the Exped MegaMat, it's closest competitor in this review. We give it a 6 out of 10.

Best Applications

Clearly, if you're considering purchasing a camping mattress, you're probably not planning to backpack the PCT with this beast in tow. The MondoKing 3D is fairly large when rolled up and at 5lbs 8oz. it's relatively heavy. Being spacious, comfortable, and easy to use, the MondoKing is a great car camping mattress. With it's large, cozy features, the MondoKing may well make even those who have given up on comfortable camping fall in love with sleeping outside again. Our tests suggest that the supportive foam core is a strong contender as an elegant solution for back pain and pressure points. We would feel confident in our city-dwelling cousin's comfort while weekend camping on this delightful camping pad, and excited to swap stories and secrets while both fitting happily into a two-person tent.


Priced around $180, the MondoKing 3D is on the more expensive side of the self-inflating camping mattresses we tested. Depending on where you look, the MondoKing and the Exped MegaMat are about the same price, which according to how well they performed in our tests — and outperformed the competition — makes sense. Despite being a decent chunk of change to throw down on a camping mattress, we think you'll find the comfort and versatility of the MondoKing 3D Large is well worth the dough.


The Therm-a-Rest MondoKing 3D Large is our Top Performer for Comfort and Size. It combines the second-highest level of comfort of all the camping mattresses we reviewed, with a slightly narrower width to fit more easily into the tent you already own. The MondoKing 3D is an excellent all-around camping solution, and we would happily recommend it to both our dirtbag, live-out-of-my-van friends as well as our hard-to-please, princess-and-the-pea family members.

Maggie Brandenburg