The 6 Best King Mattresses of 2021

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A good night of sleep is the ultimate form of restoration and rejuvenation. Everyone sleeps, of course, but not in the same way, and as a result, shoppers have different needs when it comes to choosing a king-size mattress.

There are coiled spring mattresses for those who like a traditional feel and ‘bounce’ to their mattress. Foam mattresses provide a contour cushion that relieves pressure points and creates a supportive sleeping surface. Hybrid mattresses combine the best of both. Choosing what type of king mattress to purchase and how much to spend is no small task, though, as mattress manufacturers have created an abundance of options. That's why we've combed through all of your options for you.

Here, the best king mattresses for every type of sleeper.

Our Top Picks
The open-cell foam will help you get a cooler and more comfortable night’s sleep.
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If you're willing to spend a bit more, this is a firm but comfortable mattress that's also easy to assemble.
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Best for Side Sleepers:
Casper Original Mattress at Casper
The Casper Original Mattress features zoned support to help keep you comfortable while you snooze.
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For something more wallet-friendly, this is a medium-firm hybrid mattress with luxe features.
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This mattress delivers on its promise to give you a solid sleeping surface.
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For the best of both worlds, this mattress combines the support of an innerspring with the softness of foam.
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Best Overall: Tuft & Needle Original King Mattress

Tuft & Needle King Mattress
What We Like
  • Uses proprietary open-cell foam that helps you stay cool

  • The materials are third-party tested and certified for consumer safety

What We Don't Like
  • May require a break-in period

If you’re shopping for a king mattress online, it won’t be long before you come across the Tuft & Needle Adaptive Foam Mattress. This mattress carries a trio of certifications to protect consumer safety and the environment. It also aims to help you sleep cooler and more comfortable, thanks to its unique foam composition.

A common complaint with memory foam is that it’s hot and stuffy and makes it hard to move around. Tuft & Needle aims to solve these problems with a unique, proprietary open-cell foam that is supportive but won’t suck you in. To keep you sleeping cool and comfortable, this adaptative foam contains a mix of graphite and gel beads for better temperature regulation.

The Tuft & Needle king mattress is constructed of 7 inches of support foam certified to be free of PBDEs, heavy metals, phthalates, and formaldehyde by CertiPUR-US, Greenguard Gold and Intertek’s Clean Air Certification. On top of this support layer is a 3-inch layer of adaptive foam for your comfort. It’s worth noting there's little to no chemical smell when unboxing this mattress.

Tuft & Needle does recommend giving this mattress a break-in period. It may initially be firm, but it will provide softer support after a week or more of use. Overall, the Tuft & Needle king mattress is a good choice for its unique foam and environmental certifications, combined with a comfort level that works for most people seeking a good night of sleep.

Best Mid-Range: Zinus Sleep Master iCoil 13-inch Euro Top Spring Mattress and Box Spring Set

Zinus iCoil Euro Top Mattress
What We Like
  • Made with individual pocket coils and supportive foam

  • Comes with a metal box spring

What We Don't Like
  • Mattress takes 48 hours to expand

If you're willing to spend more money on your mattress, the Sleep Master Spring Mattress is an excellent choice. Most people will find this mattress offers plenty of support with enough cushion to be comfortable for a solid night of sleep.

The Sleep Master iCoil Spring Mattress is constructed with hundreds of individually pocketed coils to minimize motion transfer. To provide support, the iCoil Spring Mattress is finished with two layers of comfort foam and another layer of high-density support foam. When compared to other mattresses, the support foam layer in this mattress does a great job of maintaining the firmness and support of the bed. The pillow-top is soft enough for most people, but if you’re looking for an extra-plush feeling, you might need to add a separate topper.

We like that this king-size mattress comes with a metal box spring, which is unique for many of the bed-in-a-box mattresses available online. Just unpack the box spring, which springs into place easily, then allow the mattress to expand for up to 48 hours before laying your head down for a good night of rest.

Best for Side Sleepers: Casper Original Mattress

Casper Original Mattress
What We Like
  • Good balance of cushion and firmness

  • 100-night risk-free trial

  • Zoned support

What We Don't Like
  • May be too soft for some

The Casper Original is the brand's most popular mattress, and it offers a good balance of support and cushioning. The mattress features three zones of ergonomic support to help you sleep comfortably—the softer foam around the shoulders provides pressure relief for the upper body, while the firmer foam under the hips, waist, and lower back helps you stay aligned. What's more, the mattress uses perforated foam that allows body heat to circulate so you stay cool.

The mattress is available in two styles: An all-foam version and a hybrid that offers added support and bounce. To help you shop with confidence, Casper offers free delivery, a 100-night risk-free sleep trial, and a 10-year limited warranty.

"The Casper mattress is comprised of four layers of breathable and supportive memory foam. It also provides firmer support under the hips and softer support under the shoulders—a feature the company dubs Zoned Support. We didn’t notice any apparent differences in various areas of the mattress, but we woke up without stiff joints in either our hips or shoulders, so we’d say it works."—Katie Begley, Product Tester

Best Budget: Allswell Mattress

Allswell Mattress
What We Like
  • Budget-friendly

  • Made with individually-wrapped coils and gel-infused memory foam

What We Don't Like
  • Poor edge support

For a budget-friendly king bed, the Allswell Mattress is an excellent choice. The medium-firm mattress features individually-wrapped coils that minimize motion transfer, so you're less likely to be disturbed when your partner rolls over or gets out of bed, and there's edge support on two sides. To help prevent you from feeling too warm during the night, there's a layer of charcoal and copper gel-infused memory foam that absorbs body heat. To cap off the comfort, the mattress is covered with Allswell's signature quilted top panel.

The Allswell Mattress comes with a 10-year limited warranty, and the company offers a 100-night risk-free sleep trial so you can be sure this is the right king mattress for you. With luxe features and an affordable price, you can't go wrong with this comfy mattress.

Best Firm: Sealy Response Essentials 8.5-inch Firm Tight Top Mattress

Sealy Response Essentials Firm Mattress
What We Like
  • Innerspring mattress topped with support foam

What We Don't Like
  • May not be comfortable for side sleepers

Make no mistake about it, this is a firm king mattress that delivers on its promise to give you a solid sleeping surface. This 8.5-inch thick king mattress is an innerspring mattress that is topped with Sealy support foam to keep you from feeling the 400-plus coils inside the mattress. It’s firm yet supportive, but not as hard as sleeping on the floor. If you ask for firmness in a king mattress, this is what you want. If you're a memory foam mattress user looking for more support, we think you'll be satisfied with this tight top king mattress.

On the other hand, if you're not prepared for a firm mattress, you may find this one to be too hard. Side sleepers may also find it uncomfortable since there is little give for shoulders. However, this king mattress is a great choice for back and stomach sleepers, who are likely to enjoy this firm sleeping surface and tight top.

Best Hybrid: Olee Sleep 10-inch Omega Hybrid Gel Infused Memory Foam and Pocket Spring Mattress

Olee Sleep Omega Hybrid Mattress
What We Like
  • Five-layer construction with pocketed springs and cooling support foam

What We Don't Like
  • Poor edge support

Get the support of an innerspring mattress combined with the softness of foam with a hybrid king mattress, like this version from Olee Sleep.

The Omega Hybrid mattress has a unique five-layer construction that gives this mattress a lot of support for some serious zzz’s. In addition to the 7.5-inch pocketed springs (which sit on top of a .25-inch base foam), this mattress has 3 inches of supportive foam—with the top inch being a cooling gel foam. It’s worth noting that the springs are individually pocketed to reduce motion transfer—an important factor to consider if you’re sharing your mattress with someone else.

This mattress is super comfortable and a good choice for people replacing traditional spring mattresses that aren’t ready to commit to a solid memory foam mattress. You may find there's a lack of edge support, but that’s typical for foam topped mattresses.

Final Verdict

If you’re in the market for a king mattress, we recommend the Tuft & Needle King Mattress (view at Amazon). It’s made from their signature adaptive foam, which is supportive, bouncy, and cooler than traditional memory foam. If you’re able to spend a bit more, the Sleep Master iCoil Spring Mattress and Box Spring Set (view at Amazon) is another great option.

What to Look for in a King Mattress


There are a few different materials to choose from when shopping for a new mattress. Many mattresses are made with supportive memory foam that contours to the body. Some memory foam mattresses have features like cooling gel to make them more comfortable for hot sleepers. For a more traditional mattress feel, you can choose one with innersprings or pocket coils. And for something in between, you can opt for a hybrid mattress with foam and innersprings. 


It’s often assumed that thickness equals comfort, but material quality also affects the mattress’s overall comfort. For example, a high-quality 10-inch mattress will probably be more comfortable than a thicker, lower-quality option. Another thing to keep in mind: If you opt for a thick mattress, you might also want a set of deep pocket sheets that will fit nicely on your comfy new bed. 


You may want to select a mattress firmness based on your sleep position. Options range from soft/plush to firm, with medium-soft and medium-firm options in between, and you’ll want to be sure the mattress is supportive enough to keep you comfortable throughout the night. 

Standout Features

Third-party certifications

When choosing a new mattress, third-party certifications ensure the product has been tested for consumer or environmental safety. For example, foam mattresses with CertiPUR-US certification are free of heavy metals, ozone depleting chemicals, and other substances of concern. Similarly, Greenguard Gold-certified mattresses have met strict chemical emissions standards.


You'll want to consider the breathability of your new mattress, especially if you're a hot sleeper. While foam mattresses can be too warm for some people, you can choose one made with open-cell or ventilated foam for better breathability. For added comfort, you can also opt for a mattress with a breathable cover.

Why Trust The Spruce?

This article was edited and researched by Cristina Sanza, a lifestyle writer specializing in home products and organization hacks. To keep our mattress picks current and help you choose the right king mattress, she reads customer reviews, third-party articles, and brand websites. Our team also tests top products.

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Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. About Certified Foam.CertiPUR, CertiPUR-US, 23 Oct. 2019,

  2. Ul Greenguard Certification Program.UL, UL LLC,

  3. VOC Indoor Air Quality Certification.Voc Indoor Air Quality Certification, Intertek Group,

  4. Noyed, Daniel. “Mattress Firmness.Sleep Foundation, OneCare Media, 17 June 2021,