Casper One Mattress Review 2025

The Casper Original foam mattress changed how we buy a mattress when it launched in 2014. With its medium appeal designed to suit most sleep types, it could be ordered online without stepping into a showroom but the risk was minimal thanks to a generous trial period, and it conveniently arrived at your doorstep vacuum sealed in a very manageable box. It was the start of the bed-in-box craze, which continues to be in full effect. I initially tested this internet sensation in fall 2023, and I wasn’t that impressed. I thought it was too soft, lacked support, and retained so much heat that I woke up hot during much of my testing period. When Casper relaunched its entire mattress line, I was curious to see what changes had been made after Casper replaced its flagship foam mattress with The One, a lofty moniker that signifies your search for the best mattress should end here; it’s the only mattress you need.

I tested a queen-size version of The One in June in Texas, and I was pleased to discover improvements in Casper’s base all-foam mattress. Not only does it offer a firmer feel and better support for the lower back and hips that should appeal to back and stomach sleepers, but its temperature regulation has improved by leaps and bounds, resulting in more bang for your buck.

Keep reading for the full review of The Casper One mattress to see how it fares among the best foam mattresses. Don’t forget to consider our other Casper mattress reviews to compare which may be the best Casper mattress for your needs.

Construction

The Casper One mattress has four layers, starting with a gray soft knit cover that’s soft to the touch while remaining breathable. The top comfort layer is an open-cell polyurethane foam that works to increase airflow and breathability. A layer of memory foam follows, providing a cradling effect for sleepers. The final and thickest layer is a support core of polyurethane foam intended to prevent the mattress from sagging over time.

Interestingly enough, Casper does not directly note on its product page that its foams are CertiPUR-US certified, which means that the foams have been tested to be made without harmful chemicals and materials, and it is frankly an industry standard among foams. Casper confirmed with us that the foams are indeed CertiPUR-US certified, which we cross-checked with the CertiPUR-US directory. Casper does make it crystal clear that the mattress is fiberglass-free and assembled in the United States.

Our review of the Casper One Mattress

Setup

Casper ships all their mattresses in cardboard boxes straight to your front door with UPS. Shipping is free and takes 2-8 business days. They do not offer expedited orders, though with multiple Casper locations around the country, you can find their mattresses in stores, too, if you want to buy and bring one home the same day. A white glove delivery service (with optional product removal) is offered for $249, though it may take two to four weeks for the mattress to be delivered with their shipping partners.

Upon receiving the Casper One mattress, I moved it from my front porch to my guest bedroom. The mattress is quite light, the queen weighs 76 pounds, so it was easy to move by myself.

After removing the mattress from the cardboard box, I placed it on my platform bed and removed the plastic wrapped around it. There was a slight off-gassing odor, but it disappeared within the hour. The mattress seemed to expand immediately, and I was able to sleep on it that night. According to Casper, their foam mattresses can be slept on right away but might take 48 hours to fully expand.

Comfort and Support

I’m a 5’5″ midsize woman, and I can sleep comfortably on my back, stomach, and side on medium-firm mattresses that balance softness with support. From the get-go, it was clear that the Casper One is a firm mattress, despite the brand describing it as “medium-firm.” While there is a bit of softness to the top layer, my body didn’t sink in. I felt slightly cradled but mostly supported. It also makes it easier to shift positions without feeling stuck in bed. Overall, I’d give it a 7.5 out of 10 on the firmness scale.

I was so firmly supported that I was able to comfortably lie on my stomach and back; however, most nights, I primarily slept on my stomach, making me inclined to recommend the Casper One to stomach sleepers. The mattress felt too firm to comfortably sleep on my side. In fact, the first week of testing, I awoke with a sore back, which surprised me since I actually slept quite deeply and through the night without much movement. After a week, the soreness disappeared. I wouldn’t say I woke up with more relief from pressure points, but at least I wasn’t sore.

Heat dissipation

I was initially nervous to test the Casper One because I found its predecessor, the Casper Original trapped and retained heat so much so that I woke up hot during most nights of the review process. I’m thankful to report that was not the case with The One mattress.

Instead, I slept on this mattress comfortably and felt that it was quite breathable even on warm June days in Texas. For reference, I slept on The One mattress with microfiber sheets, a light comforter, and the AC set at 77 degrees. I never woke up warm, sweating, or uncomfortable.

To further test the heat dissipation, I used a thermometer and found the temperature of the mattress to be 77 degrees. After lying on the mattress, it read 83 degrees on a thermometer. Two minutes later, the mattress’ temperature had dropped to 78 degrees. With all this in mind, I would say that The One is a good foam mattress for those who sleep warm.

Edge support

Top-notch edge support ensures a mattress maintains its structure over time. On a day-to-day basis, it can mean lying comfortably near the edge without rolling off or the ease and support of getting in and out of bed. The Casper One mattress doesn’t have the best edge support, which is not surprising considering it’s an all-foam mattress with no reinforced edges.

Though I didn’t dip or slip when lying near the edge, and I could lie 90 degrees along the edge without falling, the edges did not hold up when I sat on them. With a tape ruler, I measured the top of the mattress at 21 inches off the ground. Upon sitting along the sides, it dipped to 14 inches, which is a 7-inch difference. In fact, I had to take care not to slip off during this test.

If you have mobility issues, getting off and on this mattress might be difficult. At the least, I wouldn’t advise getting dressed while sitting on the side. However, you shouldn’t have any problems with lying near the edge if you have a partner who pushes you to the periphery of the bed while you sleep.

Motion isolation

A mattress with good motion isolation ensures that two people can sleep soundly without the other person’s movements disturbing them at night. The One mattress excels in motion isolation. I discovered this in two ways. I had a friend lie on the mattress and move positions; I could not feel their movements, which didn’t surprise me since the mattress isn’t bouncy but absorbs motion and weight.

Then I ran another test which involved placing an unopened soda can in the middle of the bed and my phone with a vibrometer app 12 inches away. On the opposite side of the can, another 12 inches away, I dropped a 15-lb. weight from four feet five times. Not only did the can stay upright during the dropping of the dumbbell, but it resulted in a mean reading of 2.6, and an “I” or “Instrumental” reading. This indicates that the vibrations were the lowest they could be for the app to record.

Although the edge support isn’t the best, I’d still say The One is a good mattress for couples, considering the motion isolation and the fact that you won’t slip off while lying near the edge.

Trial period and warranty

Casper mattresses comes with a 100-night trial and free returns, though the company requires customers to sleep on the mattress for 30 days before returning, as it can take your body that amount of time to adjust.

If you’re a cautious buyer who wants to see the mattress in person before purchasing, Casper has several Sleep Shops around the country, and partnerships with retailers like Rooms To Go, Relax the Back, Mattress Warehouse, and more to see if it’s right for you.

The Casper One has a 10-year limited warranty, which is fairly common among foam mattress brands, considering foam has a shorter lifespan than other materials. The warranty covers visible indentations greater than an inch and any physical defects in the foam or zipper. I like that Casper covers shipping costs if the mattress needs to be shipped to them to be repaired or if they send you a replacement.

Cons to consider

I wouldn’t necessarily call The One’s firmness a drawback, only because some people really thrive sleeping on firm mattresses. I prefer a slightly less firm mattress than The One offers, but at least I was able to sleep on my stomach comfortably enough. It’s a great fit for back and stomach sleepers, though if you sleep on your side, you’d do well to check out our mattress guide for side sleepers.

The Casper One does not have the greatest edge support. In fact, it’s quite bad. When sitting on the side, I dipped seven inches, and I had to take care not to slip off. Having said that, I didn’t have any issue sleeping near the edge. The bed didn’t dip, and I could actually lie 90 degrees without falling off.

What are your alternatives?

To stay within the Casper mattress family, you could always consider the Casper Dream. It’s a hybrid mattress with better edge support than The One, and lands as a true medium firmness. Our tester gave it a 6 out of 10 on the firmness scale, and also suggests it for back and stomach sleepers. He appreciated the zoned and considered it one of the coolest mattresses he’s tested. Strict side sleepers will be better off deferring to the Dream Max Hybrid for a plusher feel that provides more pressure relief. We’re pretty content with the heat dissipation properties of the base Casper mattresses, but if you need to sleep even cooler, the Snow hybrid mattresses incorporate Phase Change Material and aluminum graphite “Heat Delete Bands” to sleep five degrees cooler. Casper no longer promotes the Original Casper Mattress on its website, but it still has availability through Amazon if you want the original version.

The Nectar Classic Memory Foam Mattress is a great memory foam alternative that is much more affordable than the Casper One. It costs about $650 for a queen versus $800-$1,000 for The One. Plus, it offers a more true medium firm feel, great motion isolation, and better edge support. The temperature regulation might not be the best, but with a year-long home trial, you have plenty of time to see if it’s a fit for you or not.

If you need a softer foam mattress ideal for a side sleeping position, I love the GhostBed Luxe. Not only is it incredibly comfortable, but it will also keep you cool at night. Thanks to its edge support and temperature regulation capabilities, it’s an ideal choice for couples. Just be prepared for a slightly higher price than the Casper The One, typically costing around $1,500. This price tag feels justified, though, going into the more complex and varied foam constructions spanning eight layers.

Check out our guide to the best mattresses for more recommendations.

The bottom line

The One is Casper’s entry-level foam mattress and while it may be firm and take a week to get used to, it’s supportive enough for back and stomach sleepers and does a great job in terms of breathability and temperature regulation. It’s difficult to say that it’s ideal for couples when the edge support is so poor, but that applies to the sides of the bed as opposed to cratering if you sleep near the edge, which is a win in my book. Casper definitely improved their basic design when they went from the Original to The One, and we’re sure to see more Casper fans investing in this foam mattress.