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King-Size Bed Dimensions: How to Know If It Will Fit in Your Bedroom

Here's everything you need to know about king-sized mattresses and what to consider before buying one.

Lena Borrelli Contributor
Lena is a contributor for CNET.
Lena Borrelli
5 min read
End of mattress close-up
Kinga Krzeminska/Getty Images

Not getting enough sleep can have serious repercussions. It can affect your mental health, prematurely age your brain and even affect how long you live. 

Part of getting the right amount of sleep is having the right mattress. But before you can buy your new bed, you need to know the right mattress size for your room. A king bed gives a ton of space for sleep and makes room for sleeping partners, but it also demands a lot of space in your bedroom. 

If you are thinking about buying a new king bed for your bedroom, this is what you need to know before you go shopping.  

King-size bed dimensions

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The standard king bed measures 76 by 80 inches with a surface size of 6,080 square inches. It can also be made from two twin mattresses pushed together, with each twin bed typically measuring 38 by 80 inches. It makes a king a bit longer than a California king bed but not as wide. In comparison, a California king measures 72 by 84 inches. Meanwhile, a queen bed is the same length as a king bed but not as wide, measuring 60 by 80 inches. When deciding between a king vs. queen bed, it all has to do with how wide you want your bed to be. If you are taller, a California king will give you the extra length to comfortably fit your height.  

However, it is important to note that measurements can vary slightly based on the manufacturer, so be sure to check the measurements before you buy.

To see how a king bed compares, this is an overview of mattress measurements by size

Mattress sizeDimensions (in inches)
Twin 38 x 75
Twin XL 38 x 80
Full 54 x 74
Queen 60 x 80
King 76 x 80
California King 72 x 84

What to consider when choosing a king-size mattress

When buying a king-size mattress, there are a few factors to keep in mind to help ensure you find the best mattress for your bedroom.    

Room size

It is critical that your bedroom is large enough to accommodate a larger bed. A king-size mattress is best in a bigger room in your house, such as the master bedroom. Remember, your bed frame will also add a few inches to the mattress. Experts recommend a minimum room size of 12 by 12 feet. Generally, 30 inches of space around the bed is enough room for you to move around the bed. Be sure to also account for any other furniture in the room that may take up extra space, and check to ensure that the mattress will fit through the door frame. The last thing you want is a brand-new mattress that won't fit through the door. 

Individual sleep preferences

With different body shapes, it is not uncommon for many couples to have separate sleeping styles. One of the best parts about a king bed is that you can use two separate mattresses to make one bed. That means you can choose the best mattress for side sleepers while your spouse enjoys the best mattress for back pain. Twin mattresses are much cheaper than a king size bed and can be easily customized to your preferences, no matter on which side of the bed you sleep.  

Compatibility with bed frames

A king is one of the most popular bed sizes, so you will have lots of options. Just be sure that your bed frame actually fits your mattress; with the average 76 by 80 bed frame, it should be just a little wider than your mattress. Remember that sizes can vary by manufacturer, so double-check dimensions for both to ensure a snug fit. 

Co-sleeping

A king size bed is a great fit for those who don't sleep alone -- although there is something to be said about the luxury of a king bed to yourself. However, many of us share our beds with another body -- a partner, a child or a pet. A king bed has enough room to help ensure that your kids or your Saint Bernard don't cramp your sleep style.   

Popular king mattress models 

Now that you know it will work for your sleeping habits, it is time to find the best king size mattress for your needs. 

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Jonathan Gomez/CNET

The Brooklyn Bedding Signature earns our pick for best overall, thanks to its high-quality hybrid design with three firmness levels and nearly 1,000 pocketed coils that provide excellent body support for all body types. It is reasonably priced, too; it normally retails for $1,600, but you get it on sale now for only $1,200. That includes a 10-year limited warranty. If you find yourself suffering from back pain, the Amerisleep AS2 Hybrid Mattress could be the best king for you. 

It incorporates firm edge-support reinforcements, so there's no sagging, just a medium-firm construction with Bio-Pur memory foam. It's normally $1,550, but it is on sale for $1,099. There is also the Allswell mattress, which is the best budget king size mattress you can buy at less than $400 total. It comes from parent company Walmart and features a hybrid build with a foam and pocket coil system. It is perfect for the combination sleeper who changes from their back to their stomach throughout the night. 

Tips for shopping for a king-size mattress

No matter which mattress you choose, there are a few things to keep in mind. 

  • Budget: You don't have to break the bank to find a new mattress. The average mattress runs around $1,000, but it is possible to find mattresses for just a couple hundred dollars. With so many options available, search your options to find a quality mattress brand within your budget. 
  • Primary sleeping position: How you sleep can also help you find the right mattress. Side sleepers generally prefer soft to medium-firm mattresses, while back and stomach sleepers typically benefit from a firmer mattress that provides better support. There are also hybrid mattresses that help combination sleepers find a medium support that works with all sleeping styles. 
  • Testing: Reading about a mattress is a lot different than trying one. If you can, go to a mattress store to personally test out different mattress types to find the best one for you. Once you narrow down your list, check out reviews to see user experience. Pay particular attention to quality, construction, delivery and how long the mattress actually lasts.   
  • Policies and procedures: Before you buy, ask if there are any warranties to secure your purchase. Also, ask about shipping policies and how to handle returns if there is an issue with your delivery. 

King-size mattress FAQs

What are the dimensions of a king mattress?

The average king mattress measures 76 inches wide by 80 inches long. However, dimensions can vary slightly between manufacturers, so be sure to confirm measurements before you buy.

What is the actual size of a king size bed in feet?

A king-size bed is 6 feet, 4 inches in width and 6 feet, 8 inches in length.

What are the measurements for a king-sized bed frame?

The standard king-size bed frame measures 76 by 80 inches, making it just a bit wider than your mattress. However, sizes can vary slightly here, as well.

Will a California king mattress fit a king frame?

No, a California king mattress does not fit a king frame. A king mattress is wider, so you will have a few inches hanging over the side of the frame.  

How big is a California king compared to a king?

A California king measures 72 by 84 inches compared to the king size bed that measures 76 by 80 inches. That makes a California king longer but not as wide.  

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.