Serta iComfortECO foam mattress review: The best firm mattress we’ve tested

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Before the bed-in-a-box industry took off in the 2010s, there were three major mattress brands: Serta, Simmons, and Sealy. They’ve since merged (Serta with Simmons, Sealy with Tempur-Pedic) and still produce some of the best mattresses with modern materials.

The Serta iComfortECO Foam Mattress gets its name for including eco-friendly materials, though it isn’t organic. The memory foam design is available in firm, medium, and plush firmness optionss and three design levels. I tested the firm standard model, which costs more than the medium and less than the plush. It comes with Serta’s in-home delivery and 120-night risk-free return policy, both impressive for the bed’s price point. It is a great option for couples, cold sleepers, and back and stomach sleepers. Below are the details of my experience.

The Serta iComfortECO Mattress is available in three styles: Standard, Enhanced, and Ultimate and three firmness levels. I tested the Standard, which is its base model design and consists of a cool cover made of Repreve fabric, an eco-friendly material used in various textiles. The foam layers from top to bottom are

The Enhanced features additional layers, adding to the thickness. It’s 14 inches thick, while the Standard is 12.5 inches. The Enhanced has additional comfort and support foam layers. The Ultimate is the priciest option; it’s 15 inches thick with an additional memory foam layer for pressure point relief.

These days, most mattresses you buy online arrive at your door compressed in a box, and you’re left to schlep the heavy box to your room and set up the bed yourself. That’s not the case with the Serta iComfortECO, as the in-home setup is included in the bed’s cost.

Serta contracts with a local delivery company to coordinate a delivery time with you. The delivery company typically offers a four-hour window of when the mattress might arrive. The crew nailed the delivery time and were in and out in under 10 minutes. The iComfortECO comes fully expanded, though it had a mild “new bed smell” that dissipated by bedtime.

The iComfortECO has three firmness options: Firm, Medium, and Plush, of which I tested the Firm. Of note, not all firmnesses are available in all three styles.

I’m a side sleeper and a little bigger than your average person. Like most side sleepers, I generally prefer a softer mattress. In the past, I’ve avoided testing firm mattresses, but I do it to serve readers who are looking for a firm mattress. Well, I was blown away by how comfortable the Serta was.

The Firm was among the firmest mattresses I’ve ever tested. On a scale of 1 to 10, with 10 being the firmest, I’d put it at an 8. Yet, when lying on my side, my spine stayed aligned thanks to the foam sinking just enough in my heavier areas. This also helped relieve pressure, so I didn’t wake up with aches or pains.

I track my sleep quality using a Garmin Forerunner 945 smartwatch. My average sleep score over the years is about 63, with 100 being the best. While sleeping on the iComfortECO, I had several nights in a row over 70 and even a couple in the 80s. I never thought that was possible for me, especially as a side sleeper on a firm mattress.

To test how cool mattresses stay, I use an infrared laser thermometer to take surface temperature readings before lying down at night and right after getting up in the morning. Then, I take another reading two minutes later to assess the heat dissipation.

The iComfortECO did poorly in both measurements. The bed seemed to trap heat. I’m a hot sleeper, and I awoke a few nights sweating. The bed also didn’t dissipate heat well. The temperature only dropped about 10 degrees Fahrenheit within two minutes of getting up. By contrast, the median of the picks in our best cooling mattress guide is a 14-degree drop. This mattress will better suit cold sleepers.

When a mattress has good edge support, you feel more supported as you lie and sit on the side. It gives you more sleeping area if your partner tries to take over your side.

To test edge support, I sit on the bed and measure how much the side sinks. I also lie on the very edge and slowly roll off to see how far I can go before I fall. If my body reaches a 45-degree angle to the bed, then the mattress has good edge support.

The Serta iComfortECO Mattress has the best edge support of any mattress I’ve tested. I was also able to roll quite far before falling off. When sitting on the edge, it only sank about 2.5 inches. The average is 3.5 inches.

A mattress with good motion isolation will keep you from being disturbed as your partner shifts at night.

I drop a bowling ball onto the bed to test motion transfer and measure the intensity of the vibrations on the other side of the bed. I also place a soda can upright one foot from the impact point. If the can remains upright, the motion isolation is excellent. The Serta passed this test, and it registered below-average vibrations. This mattress has impressive motion isolation, making it a smart choice for couples.

Serta offers a lengthy 120-night trial period, and if you don’t like the mattress, you get a full refund.

The warranty is 10 years and covers ¾-inch sagging or body impressions or normal wear on the cover. However, you must use a proper foundation with the iComfortECO. If your bed qualifies under the warranty, Serta will repair or replace it, but you’ll be responsible for the shipping costs. Read the details of Serta’s 10-year warranty.

The Serta iComfortECO Foam Mattress trapped heat, and it didn’t cool down quickly when I got up from it. This might be a pro for cold sleepers, but I slept hot and awoke sweating a few nights. For more details, see the heat dissipation section above.

Unlike most memory foam mattresses, the Serta iComfortECO didn’t cradle my body and relieve pressure as much as I would have liked. This may well be because I tested the firm version.

The main negatives of the Serta iComfortECO are it doesn’t dissipate heat well or cradle the body as one may expect from traditional foam mattresses. If these features are important to you, then the Tempur-Pedic Cloud Mattress may be your better option. It did the best job of cradling my body and relieving pressure of any mattress I’ve tested. It also stays cool. I slept really well on it, no matter what position I was in. However, it costs about $300 more than the Serta and has poor edge support. Read our full Tempur-Pedic Cloud Mattress review.

While I have not tested the other mattresses in the line, the iComfortECO is offered in medium and plush options, which may cradle your body better. The Ultimate and Enhanced models may also add extra comfort. Or, choose a hybrid mattress from the line. The iComfortECO Smooth Hybrid replaces the durable foam core with individually wrapped pocket coils with zoned support for pressure relief where you need it most. The Quilted Hybrid adds a quilted foam top layer with an optional plush pillow top.

For more recommendations, check out our guide to the best mattresses.

The Serta iComfortECO is the best firm mattress I’ve ever tested. While offering impressive support to the very edges, it provided just enough pressure point relief to keep me comfortable, even while sleeping on my side. The motion isolation and edge support make it ideal for couples, and while it traps heat, this could benefit the cold sleepers out there. Overall, this is an outstanding bed, especially at this price point.