Tom's Guide Verdict
The Casper One has a medium-firm bed feel that offers plenty of give for pressure relief and delivers excellent support. That said, we think it suits back and stomach sleepers the most. Lighter weight to average weight side sleepers will need to give themselves time to settle into this one. We think couples will appreciate the superb motion isolation, but if you prioritize strong edge support and cooling effects, look elsewhere (we recommend alternatives in our review). Otherwise we feel that Casper's The One is a reasonably priced memory foam mattress in a box that offers the comfort and support most back and stomach sleepers are searching for.
Pros
- +
Great for back and stomach sleepers
- +
Outstanding motion isolation
- +
Reasonably priced
Cons
- -
Too firm for light side sleepers
- -
Mediocre edge support
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Casper One Mattress review in brief
The Casper One Mattress is an upgraded version of the Casper Original mattress in a box. It isn't so much a major departure from the previous model as it is a facelift.
Whether you’re a returning Casper customer or a new customer who's curious about trying one of the brand's mattresses for the first time, here we're sharing everything you need to know about the Casper One after three weeks of testing one ourselves.
Our full Casper One Mattress review is below, but if you're short on time, here’s a quick run-down of what we discovered during testing, what you can expect for yourself when sleeping on it, and whether it's good enough to be ranked as one of the best mattresses you can buy this year.
Type: Memory foam
Materials: Memory foam, polyfoam
Firmness: Medium-firm
Height: 11”
Trial period: 100 nights
Warranty: 10 years
Price: From $749 at Casper
The Casper One Mattress (also simply known as "The One") is a three-layer memory foam mattress wrapped in a knit cover. It's rated medium-firm by the brand, although we found it skews slightly firmer. It's an ideal choice for stomach and back sleepers, yet it's not so unyielding for those who like a softer surface, such as side sleeper — although you'll need some time to break it in.
The firm surface of the Casper One held up beautifully during the night, allowing our tester and her partner to reap the full benefits of a supported, pressure-relieving sleep. It also has excellent motion isolation and would be a great buy for couples who wake and sleep at different times. Our lead tester didn’t feel her partner move in or out of their queen-size bed.
On the other hand, the Casper One's edge support is lacking; under concentrated weight, it dips significantly. Meanwhile, temperature regulation is average. We tested it during the wintertime so overheating wasn't too much of an issue, but we did notice some heat retention when we cranked up the thermostat.
Those faults aside, we think the Casper One is a good value for the cost. A queen retails for $999 but regular mattress sales drop the price into the mid-range bracket, around $800 or less. If you want to snag the lowest prices for a Casper One, we recommend waiting for Memorial Day sales in May.
That's our Casper One Mattress review in a nutshell. Keep reading for complete details about pricing, design, performance, and setup...
Casper One Mattress review: Price & trial
- Replaces the Casper Original as the brand's entry-level model
- Queen retails for $999 but regular discounts knock 20%-30% off
- Comes with a 100-night trial and a 10-year warranty
The Casper One is the least expensive in the brand's revamped lineup, with a queen retailing for $999. Fortunately, regular Casper mattress sales cut 20% to 30% off this already-affordable all-foam bed. Larger discounts usually take place around major holidays and events such as Presidents' Day, Memorial Day, and Black Friday
Here are the retail prices for all sizes of the Casper One Mattress as of March 2025:
- Twin MSRP: $749
- Twin XL MSRP: $799
- Full MSRP: $899
- Queen MSRP: $999
- King MSRP: $1,399
- California King MSRP: $1,399
- Split King MSRP: $1,498
How does that compare to its predecessor, the Casper Original Mattress? The Casper One retails for up to $300 less — and since sales have become common since Casper updated its mattress lineup in 2024, The One is often available for even less.
The Casper One comes with free shipping and returns, a 100-night risk-free trial, and a 10-year warranty. Those are the industry averages and what you'd expect from a mid-range mattress in a box.
Casper One Mattress: Design & materials
- A basic memory foam mattress with three layers
- Wrapped in a non-removable knit cover
- Fiberglass-free design with CertiPUR-US certified foams
The Casper One mattress is 11" tall and features three layers of foam. On top is an open-cell Breathe Flex Foam the company says promotes airflow and cooling.
That's followed by a layer of Align Memory Foam for pressure relief. The foundation of the mattress, known as the Casper Core, is meant to prevent sagging. The mattress is encased by a knit cover that has a texture similar to a thin sweater; you can't remove it.
Casper uses foams that are CertiPUR-US certified, meaning they're low in VOC (Volatile Organic Compound) emissions and made without harmful chemicals. The Casper One doesn't contain fiberglass but instead uses rayon-based fibers to act as a flame barrier.
Casper One Mattress review: Comfort & support
- A medium-firm mattress — a 7 out of 10 on the firmness scale
- Excellent pressure relief balanced with sufficient support
- However, our side sleeping tester needed time to break it in
Casper bills this mattress as medium-firm, and we're inclined to agree — although we'd say it's on the firmer side of that scale. Our lead tester prefers a soft, plushy bed and was hesitant to sleep on the Casper One because she thought it would be too stiff. However, she was pleasantly surprised at the slight give of this mattress.
Sleeping on her back and stomach worked well for our lead tester, but she did run into an issue sleeping on her side at first. Coming from an exceptionally plush mattress, the firmness of the Casper One took some getting used to.
The first few nights of side sleeping on this bed, she'd wake up with tingles in her arm. After a week, that dissipated, likely due to her body adjusting to a firmer surface and minimal sinkage.
We objectively tested the pressure relief of the Casper One by placing a 56lb weight on the surface. The dumbbell sank about 4 inches.
That said, this small area of weight isolation caused a bigger depression than when our lead tester and her partner slept on the Casper One. While they did sink slightly, they still felt aligned throughout the night. Our lead tester even experienced a noticeable decrease in her morning back pain during her time with the Casper One.
Score: 4 out of 5
Casper One Mattress: Delivery & setup
Setting up the Casper One mattress was a challenge. Our lead tester unboxed it herself and was met with a mattress much thicker than she initially anticipated, and that was before the mattress was fully inflated.
The bed comes compressed and rolled, and when the outside layer of protective plastic is removed, the mattress immediately inflates.
This becomes problematic due to the second layer of plastic protecting the interior of the mattress. Upon removing the first layer of plastic, the mattress begins to immediately inflate. It felt like a race against time to remove the second layer of plastic before the mattress fully expanded.
However, we consider that a plus because the strong packaging kept the mattress damage-free, and the instant inflation cut down on the amount of time we needed to wait before sleeping on it.
This isn't a lightweight mattress — a queen Casper One mattress weighs 76lbs — and adjusting it on the bed frame while it inflated made our tester break a sweat. We recommend having a second person on hand to help maneuver the mattress and remove the second layer of plastic so the unboxing process is easier (and less sweaty).
Casper One Mattress review: Performance
- Superb motion isolation — great for couples
- Temperature-neutral, but prone to sleeping warm
- Edges are sturdy but sag under a concentrated grip
For three weeks we slept on a queen-size Casper One Mattress, evaluating its motion isolation, temperature regulation, and edge support according to our testing methodology. Here's what we found...
Off-gassing
We noticed minimal off-gassing immediately after opening, but the lingering scent was minor compared to other mattresses our tester has purchased and slept on. Within a few days, there was no smell at all. Other reviews have had a different experience, but unboxing your mattress as soon as possible in a well-ventilated room can help prevent significant off-gassing smells.
Score: 4.5 out of 5
Motion isolation
To objectively measure the Casper One's motion isolation, we placed an empty wine glass on one side of the bed and then dropped a 10lb weight 25" away from it at 4", 8", and 12" above the surface.
There was a minor wobble when dropping the weight 4" away from the wine glass, but at no time did the glass tip or fall over. We repeated the tests twice for confirmation but the results were the same each time. The motion isolation here is simply exceptional.
Since our lead tester shares a bed, we were also able to gauge its motion isolation through everyday use. Our lead tester's partner wakes up much earlier than she does and with their previous bed, the movement from him getting up would startle her awake.
That was not the case with the Casper One. Our lead tester didn't wake up when her partner got up before her, which was a welcome change from their old mattress. Both of them are middle-of-the-bed sleepers and tend to huddle close to each other during the night, yet even when he got up right next to her, the movement was confined to the area immediately surrounding his body.
Memory foam mattresses are often known for their ability to dampen movement, and the Casper One is among the best we've tested in this category. Based on these results, we'd recommend it as a mattress for couples with different sleep schedules or a fidgety partner.
Score: 5 out of 5
Temperature regulation
We tested the Casper One during January and, in general, found that it slept temperature-neutral. However, our lead tester did notice a bit of extra heat retention when she bumped up the thermostat in her apartment during extra chilly days.
The thickness of the cover felt warm beneath the sheets, especially when we had the heat turned on. It didn’t make the mattress too warm, but we do feel that the cover negated the effects of the Casper One's breathable foam layers.
If you're a hot sleeper or dealing with night sweats then we suggest going for a specialist cooling mattress. Casper makes two of them — the Snow ($2,495 for a queen) and the Snow Max ($3,795 for a queen) — but they cost a lot more than The One.
Score: 3 out of 5
Edge support
Although the perimeter of the bed is sturdy under both a 56lb test weight and the weight of a human body, we deducted two points due to the depression of the mattress on the very outer edges.
Beneath a concentrated grip (such as under our tester's hands as she lifted herself from a seated to standing position), the edge of the bed dips more than other areas. This wasn't an issue for our able-bodied tester, but someone requiring strong support when getting up and down may want to avoid putting too much pressure on the sides of the bed while standing to stay steady.
Score: 3 out of 5
Casper One Mattress review: User reviews
- Rated 4.4 stars out of 5 at Casper (March 2025)
- Positive reviews for pain relief and easy delivery process
- Several customer complaints about off-gassing
At time of publishing this review The One had an overall rating of 4.4 stars out of 5 at Casper from tens of thousands of reviews. However, it appears that there's no separation between reviews for The One and Casper's previous entry-level all-foam beds, although it'll usually indicate when the review is for a different model.
Still, most buyers seem satisfied with their Casper One, citing the mattress as a solution to their problems with aches and pains. Some users also commented on the quick and easy delivery and excellent customer service. However, several reviews noted the off-gassing smell The One had after opening, so keep that in mind if you’re sensitive to scents.
Should you buy the Casper One Mattress?
If you’re looking for a medium-firm mattress that won’t break the bank, consider the Casper One. It’s got enough give to be comfortable but still offers plenty of pressure relief and support that people with aching joints will appreciate.
We think this is the best Casper mattress for back and front sleepers. Side sleepers may not find it comfortable, at least at first, but our tester eventually settled in.
The exceptional motion isolation makes it a great pick for couples, and as long as you don't regularly sleep hot, you should find it cozy. After three weeks of testing, the Casper One still springs back to its original shape no matter what type of weight is placed on it, so we doubt this bed will slump over time with proper care, although the lack of sturdy edges could be an issue for sleepers with mobility issues.
Based on its simple three-layer foam construction, we don’t anticipate the Casper One getting much softer with each night’s use, so plush bed lovers may want to consider a different model for their sleep needs. Hot sleepers won't find the cooling relief they need here, either. If you resonate with one or both of those scenarios, consider one of the alternatives below.
Casper One Mattress: Alternatives to consider
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