Best Firm King-Sized Mattress
The best place in the world to wind down and relax is your bed. It’s where you sleep, it’s where you finish the day off and it’s where the day begins. Your mattress should feel like a warm embrace every time you tuck yourself back in, so it’s important to get one that suits you perfectly, both in size and in firmness.
Many people could benefit from the extra space that king-sized mattresses have to offer. It allows for more movement, a more even distribution of weight, and room for surprise visitors such as children or pets. But, to find the perfect mattress, you first need to know what it takes to be a perfect mattress.
| Rank | Product | Highlights |
| #1 |  Novilla 10-inch Gel Memory Foam Mattress
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| #2 | 
Sweetnight 10-inch Gel Memory Foam Mattress |
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| #3 |  Sweetnight 12-inch Soft Pillow-Top Mattress
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| #4 | 
Classic Brands Cool Gel Chill Memory Foam 14-Inch Mattress |
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| #5 |  TUFT & NEEDLE Original King Adaptive Foam Mattress
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Table Of Contents
- Mattress Types
- Innerspring
- All Foam
- Latex
- Hybrid
- Mattress Sizes
- What Type of Sleeper Are You?
- Hot vs Cold
- Front, Back, or Side Sleeper?
- Why Choose a Firm Mattress?
- When is it Time to Replace Your Mattress?
- Best Firm King-Sized Mattress Reviews
- Novilla 10-inch Gel Memory Foam Mattress
- Sweetnight 10-inch Gel Memory Foam Mattress
- Sweetnight 12-inch Soft Pillow-Top Mattress
- Classic Brands Cool Gel Chill Memory Foam 14-Inch Mattress
- TUFT & NEEDLE Original King Adaptive Foam Mattress
- Conclusion
Mattress Types
Innerspring
First, there are innerspring models. These innerspring mattresses have coils sandwiched between polyfoam layers, so the springs don’t puncture the bed or poke you at night. Even within this category, there are different coil types you can come across such as those listed below.
- Bonnell Coils – These springs are hourglass-shaped and usually not found in higher quality mattresses, so they may be a sign to avoid rather than invest in the mattress.
- Offset Coils – Like bonnell coils, these are hourglass-shaped, but they are of higher quality. These coils have a flattened bottom which hinges and creates a sturdier base for the pressure of the coil to balance out.
- Continuous Wire Coils – All these coils are made with a single steel wire that joins together at the sides. This is a durable design, but it does tend to restrict the conforming movement of the mattress itself.
- Pocketed Coils – Finally, there are pocketed coils which more often than not are found in hybrids of foam and innerspring. They work best to make sure there’s little to no noise and less motion transfer if you or your partner move.
All Foam
All-foam mattresses will have numerous layers that all serve their purpose; comfort, breathability, cooling, conformation, and support.
Memory foam layers are the best at support and conforming to your body size and shape. They offer the best help in aligning your spine and relieving pressure points.
Gel memory foam takes memory foam to a whole new level of functionality (and price) with its ability to stay cool throughout the night and not swelter with body heat, something normal memory cannot do.
High-density foams will almost always be present in your mattress since this is the support layer, the one layer that ensures you’re not sinking into the bed at night and your weight is evenly balanced for the most restful sleep you can get.
Latex
Latex is a material that is extracted from the sap of rubber trees. It’s either natural or extremely synthetic. Latex has a longer lifespan as is very well known for its motion isolation and its lack of creating any noise.
There are, however, much higher chances of this mattress coming with chemical smells. They’re also heavier and harder to move around, with a considerable lack of edge support.
Hybrid
Hybrid mattresses are combinations of latex and foam, foam and innerspring, or innerspring and latex. They take the good of each side and bring them together for an even, more comfortable bed.
Of course, buying a hybrid mattress means you’re going to have to extend your price limit since these do come at a much higher price.
Mattress Sizes
There are many sizes for mattresses you’ll find which vary by mere inches, but listed below are the standard sizes for mattresses, keeping in mind that these are the four basic sizes and then there are others.
- Twin is for one person to sleep on, measuring 38 inches by 75 inches.
- Full can house one or two people, though it becomes a tight fit. Full mattresses measure 54 inches by 75 inches.
- Queen-sized mattresses are 60 by 80 inches and can have 2 people sleep on them easily.
- King sized mattresses are considered the size of greater luxury. These mattresses can have up to three people on them with dimensions of 76 inches by 80 inches.
What Type of Sleeper Are You?
Everyone has their preferences, especially when it comes to sleep. Figuring out what you prefer will greatly help you find the perfect mattress for you.
Hot vs Cold
Determine whether or not you’re a hot sleeper or a cold sleeper. If you prefer sleeping cool, then a gel-infused foam mattress may be the best option for you. Innerspring and latex also stay cool quite well.
If you prefer sleeping warm, then try to avoid mattresses that specialize in cooling since these could make your nights too cool for your comfort.
Front, Back, or Side Sleeper?
There are three positions you’ll find yourself in; either on your stomach, back, or side. If you sleep on your back or front, then you might opt for a softer mattress for greater flexibility and conformation. Side sleepers tend to go with firmer mattresses since these provide the support that you need to stay aligned.
But firmness depends on you, and what you’re comfortable with. Remember, firm mattresses don’t conform and sink at all, or only do so very little.
Why Choose a Firm Mattress?
As mentioned before, a firm mattress will provide side sleepers with greater support than any other, so side sleepers may be interested in firm options. Otherwise, some people don’t enjoy the feeling of a sinking mattress, therefore they lean towards the firmer side of filling to get a solid yet soft surface to sleep on.
When is it Time to Replace Your Mattress?
No matter how much we want it to be, a mattress isn’t a lifetime investment. There are always factors that will affect the longevity of the mattress’s life.
Firstly, every mattress that is over 7 years of age should be under investigation. There are chances of wear and tear, ripping, and even sagging with long-term continuous use.
It’s also important to prioritize your support more than anything else. If you start waking up with aches and pains in your joints, your mattress isn’t working for you.
Best Firm King-Sized Mattress Reviews
Novilla 10-inch Gel Memory Foam Mattress
Specs:
- Dimensions: 76” x 80” x 10” (or 12”)
- Thickness: 10 inches or 12 inches
- Weight: 65.21 Pounds
- Layers: 4, Gel-Infused Memory Foam, Comfort Foam, Airflow Channel Foam, High-Density Support Foam
- Cover: Bamboo and Rayon Cotton
- Warranty: 10 years limited
- Mattress Type: All-Foam/Memory Foam
Best Overall Firm King-Sized Mattress
Novilla’s mattress is a 4-layered memory foam mattress that comes in the options of 10 inches and 12 inches. There is a combination of gel memory foam, comfort foam, and high-density foam.
This helps promote an even spinal alignment and disperses your body-weight evenly for better sleep and less sinking. This relieves pressure points as you sleep for refreshed joints.
The gel-infused memory foam coupled with the bamboo cover makes this mattress great for cooling you down. It diffuses your body heat and wicks the moisture away from you at night.
The cover is also constructed with skin-friendly and breathable rayon cotton. There are fewer chances of you having reactions to bacteria and allergens.
The cover is hypoallergenic and antibacterial for a more restful and protective sleep. It’s easy to spot-clean the mattress in case of stains and spills.
Novilla has a 10-year warranty which covers manufacturer’s defects and flaws. There is also a 30-day money-back guarantee in which you can get a full refund if you’re not satisfied.
Since the mattress comes shipped in a box, it’s recommended to allow 72 hours of airing out, so the mattress gets back to its original shape as well as remove any harmful off-gassing.
Pros
- Hypoallergenic and skin-friendly cover
- Cooling bamboo cover
- Evenly balances body weight and relieves pressure points
Cons
- Corners may not inflate to full capability
Who Should Buy This?
This Novilla mattress is the best overall option for customers. It provides everything you need for a cool, comfortable and relaxing sleep. There are abundant support and comfort from the foam layers.
Sweetnight 10-inch Gel Memory Foam Mattress
Specs:
- Dimensions: 76” x 80” x 10” (12”)
- Thickness: 10 inches or 12 inches
- Weight: 81.5 Pounds
- Layers: 4, Cooling Gel Infused Memory Foam, Ventilated Comfort Foam, 3-Zoned Airflow Open-Cell Comfort Foam, Supportive High-Density Base Foam
- Cover: Rayon Cotton
- Warranty: 10 years limited
- Mattress Type: All-Foam/Memory Foam
Best Reversible Firm King-Size Mattress
Sweetnight’s mattress is unique in comparison. You can flip this mattress over and use either side. One is plush and soft with a pillow-top layer. The second side is a firmer option that uses high-density foam base for more supportive sleep.
The cover is made of 65% polyester, 30% viscose, and 5% spandex. There are four layers inside of the mattress, and there are two thickness options of 10 inches and 12 inches.
There’s a cooling gel-infused memory foam that conforms to your support and cools the surface of your bed. The ventilated comfort foam helps the mattress allow continuous airflow so bacteria don’t develop.
There is also a 3-zoned airflow open-celled comfort foam that tackles each section of your body with precision. Finally, there is a high-density base foam which acts as a level support system while you’re asleep.
There’s also edge-to-edge support so you can get in and out of bed with ease. The mattress resists sagging and prevents any rolling off. There is a 10-year warranty so you can purchase with confidence.
Pros
- Can sleep on both sides for firm/plush experience
- Motion Isolation
- Edge-to-edge support
Cons
- Strong chemical smell
Who Should Buy This?
This reversible bed is the perfect mattress to place in a guest room. You don’t know what your guests prefer, soft or firm? Once they arrive, you can use either side based on their preference.
Sweetnight 12-inch Soft Pillow-Top Mattress
Specs:
- Dimensions: 76” x 80” x 10” (12”)
- Thickness: 10 inches or 12 inches
- Weight: 114.64 Pounds
- Layers: 4, Airflow High-Density Fabric, Gel Memory Foam, Supportive High-Density Foam, Individually Wrapped Pocket Springs
- Cover: Plush-Top breathable and skin-friendly cover
- Warranty: 10 years limited
- Mattress Types: Hybrid; innerspring and Memory Foam
Best Innerspring Firm King-Sized Mattress
Next up, there is the best innerspring mattress. This mattress is a hybrid mattress that combines the comfort and cooling effects of gel-infused memory foam with the support and motion isolation of innerspring.
The individually wrapped coils adjust independently to movement. They reduce the motion transfer between you and your partner to sleep more soundly. There is localized bounce for responsiveness and proper alignment.
On the top of the mattress, there is gel-infused memory foam to help you sleep cool and provides you with body-hugging support.
The cover is a plush-top and breathable fabric with skin-friendly qualities. It wicks moisture away from the body, so you don’t wake up from sweating. There is edge support to prevent any rolling off and is resistant to overtime sagging.
Since this mattress comes in a box, it’s best to allow at least 72 hours for it to air out. It’s also best to try this mattress out for a couple of weeks since there are innerspring coils that need to regain their bounce inside.
A ten-year warranty covers this mattress in case you encounter any issues with the mattress.
Pros
- Puffy pillow cooling top is skin-friendly
- Reduced motion transfer
- Edge support and sag resistant
Cons
- Mattress may begin to sink after a while
Who Should Buy This?
Some people will never give up the comfort and support innerspring provide. For sleepers who believe foam is too dense for them to enjoy, can enjoy this firm king mattress with its natural innerspring bounce.
Classic Brands Cool Gel Chill Memory Foam 14-Inch Mattress
Specs:
- Dimensions: 80” x 76” x 14”
- Thickness: 14 inches
- Weight: 94 Pounds
- Layers: 3, Cool Gel Foam, Comfort Foam, High-Density Base
- Cover: Stretch Knit Fabric with Knit Side Panels
- Warranty: 10 years limited
- Mattress Type: All-Foam/Memory Foam
Best Cooling Firm King-Sized Mattress
A cool sleep could be the only way you sleep, and that’s fine. Classic Brands provides its customers with the ideal cooling mattress to enjoy every night.
There are three mattress styles you can choose from; Cool Gel, Cool Gel Chill, and Cool Gel Ice. Inside, there are three layers which are all foam. There is pressure-relieving memory foam, high density aerated cool-gel memory foam, and finally a high-density base foam.
The cover is made from stretch-knit fabric with matching knit side panels. The waterfall edges help you get in and out of bed with ease.
The top of the mattress is plush and comfortable for a lovely pillow-top sleeping surface. The top is also hypoallergenic and naturally resistant to allergens and bacteria. All of the foam used in this mattress is CertiPUR-US certified.
It’s adjustable base friendly and comes with 2 shredded memory foam pillows, free of charge. The 10-year warranty covers if there are any defects or flaws.
Pros
- Waterfall edges make it easier to get in and out of bed
- Hypoallergenic and antibacterial
- 2 inclusive shredded memory foam pillows
- Adjustable base friendly
Cons
- Strong chemical smell
Who Should Buy This?
A cool sleep is the best sleep for many people. With gel memory foam and breathable stretch-knit fabric as a cover, you get a cool sleep every night.
TUFT & NEEDLE Original King Adaptive Foam Mattress
Specs:
- Dimensions: 80” x 60” x 10”
- Thickness: 10 inches
- Weight: 82 Pounds
- Layers: 2, High-Density Open-Cell Foam with Graphite and Cooling Gel Beads, Original Adaptive Foam
- Cover: Breathable Plush Cover, 35% micro-polyamide 65% polyester
- Warranty: 10 years limited
- Mattress Type: All-Foam
Premium Pick
Finally, there is a TUFT & NEEDLE unique mattress. This mattress uses T&N’s original adaptive foam and an open-celled structure. Infused in this foam is graphite for cooling and gel beads.
The breathable plush cover helps you stay comfortable and cool at night. The entire mattress is GREENGUARD GOLD and CertiPUR-US certified for quality and performance. It’s also third-party tested for the best results. There are no harmful chemicals or heavy metals inside the mattress.
The combination of adaptive foam and open-celled foam allows for proper relief from aches and pains in joints. It’s also perfect for those who enjoy sleeping at a cooler temperature.
There is a 10-year warranty along with free shipping and returns. If you’re not satisfied with your purchase, you can return it within the 100-night sleep trial. Since this mattress comes inside of a box, it’s best to let this mattress air out for at least 72 hours.
Pros
- Ideal for all sleeping positions
- Unique Adaptive foam and Open-Cell Foam
- GREENGUARD GOLD and CertiPur-US certified
Cons
- Very firm for some users, little to no confirmation on the surface
Who Should Buy This?
This unique mattress from TUFT & NEEDLE is great for a long-term investment. You can enjoy a supportive and cooling mattress every night, at an affordable rate with great durability.
Conclusion
The right mattress is one purchase away, but it’s better to check first what makes a quality mattress. The specifics and your preferences are always the most important factors in finding the perfect mattress. The more space you need to sleep, the larger your mattress should be. Find the ideal firm mattress for yourself and don’t forget to share and comment below your findings for other curious readers.