Our 9” Essential mattress is a simpler take on our Original Mattress, utilizing the same dual layer memory foam technology in a slightly thinner, medium-firm mattress profile.
Shop NowKing Mattresses
One of the largest mattress sizes on the market, king size mattresses measure 76” wide by 80” long. BedInABox® king size mattresses provide plenty of bed for anyone who needs more sleeping space.
How big is a king size mattress?
A standard king size mattress is 76 inches wide by 80 inches long.
Who should sleep on a king mattress?
King mattresses give couples plenty of sleeping space, often enough for the kids or pets to climb in, too.
The king size bed is perfect for most primary bedrooms with 16 more inches of elbow room than the queen size.
Quality comfort, risk-free
Try your king mattress in a box risk-free for 120 nights. If you don’t love your new BedInABox® after sleeping on it for 60 nights, let us know and we will get the return process started. Details can be found in our Return Policy.
Certified king-size support
All of the memory foam we develop for our king size memory foam mattresses is CertiPUR-US® certified. This means that the foam has been tested by accredited labs and has been certified as safe to sleep on. We use multiple layers of our house-made memory foam to provide the perfect balance of support and pressure relief, for all sleepers.
Sleep now, pay later
We partner with Affirm to offer flexible financing options, so you can pay with fixed monthly payments with rates between 0-30% APR. Simply select Affirm at checkout and complete an application that won’t affect your credit score. Prequalify Now.
Buying a Foundation for a King Size Bed
Create a more supportive sleeping experience by pairing your king size mattress with a king size foundation. A mattress foundation serves as a base for your mattress and generally uses solid planks or slats to support and lift your mattress off the ground. There are different types of foundations suited to different mattresses and sleep preferences, BedInABox® currently offering three options compatible with a king mattress: a slatted foundation, a platform foundation and an adjustable foundation.
Clever Connect™
Provides simple, slatted support for memory foam or hybrid mattresses. This sturdy foundation is available in a 5” profile or an 8” profile and can be paired with optional foundation legs for additional height.
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Platform BedInABox®
Best described as a combination of a standard mattress foundation and a decorative bed frame, our upholstered platform offers a slightly lower profile than pairing a solid foundation with a separate bed frame and is compatible with all BedInABox® mattresses.
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MotionInABox™ Adjustable Beds
Solid mattress bases that can be raised or lowered to create a custom sleep experience. The MotionInABox™ adjustable bases are available in two different models, MotionInABox™ 1.0 and MotionInABox™ 2.0, both in the Split King size compatible with standard king size mattresses.
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More than 200,000 happy sleepers (and counting).
Which King Size BedInABox® is right for you?
The Original mattress is our classic 11” dual-layer memory foam mattress. The two layers combine plush, temperature regulating comfort and medium-firm support to provide the perfect level of contouring alignment.
Shop NowThe Azul® mattress features 11” of cooling comfort. The dual layer medium-soft mattress tops multiple layers of phase change material with an UltraCool® soft knit cover to offer our most advanced cooling system.
Shop Now11" of our classic CoolRest™ Gel memory foam construction, enhanced with spring support for added lift.
Shop NowThe Tranquillium® mattress is built with 12” and three layers of firm memory foam to maximize support without sacrificing comfort.
Shop NowThe Dual Hybrid® mattress is 13” of premium comfort, combining the support of memory foam and springs. The BedInABox® hybrid mattress features the highest coil count in the industry to provide ultimate lift, support and pressure relief exactly where you need it.
Shop NowThe Eco-Lux mattress is made with 11" of renewable memory foam, topped with a naturally moisture wicking organic cotton cover. The only Bio-Preferred® mattress on the market and our most sustainable sleep solution.
Shop NowFind your king size mattress
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Find your king size mattress
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Cozy Season Sale Items
1, 8” Clever Connect Foundation with legs.
1 MotionInABox™ Adjustable Base.
Frequently Asked Questions
What is the standard size of a king mattress?
What is the difference between a queen and a king mattress?
How many BedInABox® mattresses come in the King size?
What size room fits a king size mattress?
Is a King mattress the same size as two Twin XL mattresses?
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