King Size Mattress & Bed Frame Dimensions Guide

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Everyone wants to feel their bedroom to feel like their kingdom. It’s where you go after a long day to unwind, relax, and be unapologetically yourself. It’s where you can let your guard down and just be you. So wouldn’t you want a mattress that is also fit for a king? 

Not only do king size mattresses offer sleepers many premium features, but so many different sleepers can enjoy them thanks to their colossal size. A high quality king size mattress can turn any (appropriately sized) bedroom into a luxurious space. Mattresses are made to last for many years, which is why many people like a king mattress so they can grow into it.

If you’re ready to sleep like a king, then keep scrolling and find out whether a king mattress is right for you. 

Dimensions of a King Size Bed

The standard dimensions for a king size bed are typically 76 inches wide and 80 inches long, but keep in mind that there can be small differences between models and brands. They are specifically designed for couples and for people sharing the bed with their favorite furry friends. The more people, the more space needed, which is why a king size mattress is perfect for large families. 

In the realm of mattress sizes, a king mattress is bigger than a queen mattress, which is 60 inches wide by 80 inches long. The traditional king size mattress is smaller than Alaskan king and California king size beds. You can also get a split king size mattress, which are two identical-size mattresses (roughly the size of a twin) that equal the same size as a king size mattress. 

Interested in getting a king mattress? Check out our guide to the best king size mattresses on the market right now. 

SO GeneralMattressGraphics MattressSizeGuide
SO GeneralMattressGraphics MattressSizeGuide

Comparing King Size Beds To Other Mattress Sizes

You may be surprised to learn that there are mattress sizes larger than a king size mattress. A California King size mattress, for example, is 72 inches wide and 84 inches long. 

SO GeneralMattressGraphics Kings
SO GeneralMattressGraphics Kings

When comparing a California king to a standard king size bed, a California King is slightly narrower, but  four inches longer, which is ideal for sleepers who are very tall. IInterested in a California King? Check out this list of our picks for the best California King mattresses.

There’s also the Alaskan King size mattress, which is massive in comparison to a standard king size mattress. An Alaskan King measures 108 inches wide and 108 inches long, and is currently the largest mattress that is sold in the United States. Keep in mind that a California King and an Alaskan King may not fit in everyone’s bedrooms. 

SO Header Image Alaskan King Bed vs California King

There is also a Wyoming King mattress that measures 84 inches wide and 84 inches long, so slightly larger than a king size mattress. A Texas King bed measures 80 inches wide and 96 inches long. These are less common sizes, but select retailers do indeed supply them. 

If you and your partner have different sleeping preferences but still want to share a bed with each other, then you could also consider a split king mattress. A split king mattress is made of two identical-sized mattresses that are 38 inches wide by 80 inches long, and equal the size of a king size mattress. 

SO What is A Split King Image 3

Basically, a split king is two twin XL mattresses, since a twin XL mattress. The spilt makes it easier for partners to have a mattress that works for them specifically, without sacrificing the sleep of their partner. 

split king bed size dimensions
split king bed size dimensions

Who Needs A King Size Mattress?

A standard king size mattress is the perfect size for couples who want to be able to comfortably move, stretch, and use the entire perimeter of the bed. It is also perfect for couples who like to share the bed with their children or pets. Just like a queen size mattress, a king bed is the perfect size bed to grow into years down the road as your family grows. 

Mattress SizeDimensions (Width x Length)Best For
Twin38″ x 75″Toddlers, Children, Single Adults
Twin XL38″ x 80″Children, Single Adults, College Students
Full54″ x 75″Children, Single Adults, Adults with Children and/or Pets
Queen60″ x 80″Single Adults, Couples, Single Adults with Children and/or Pets
King76″ x 80″Couples, Couples with Children and/or Pets
Split King38″ x 80″ (each mattress)Couples with different mattress preferences, Sleepers who want to use an adjustable bed frame
California King72″ x 84″Couples, Couples with Children and/or Pets
Wyoming King84″ x 84″Couples, Couples with Children and/or Pets
Texas King80″ x 96″Couples, Couples with Children and/or Pets, Tall Adults
Alaskan King108″ x 108″Couples with different sleeping positions, Couples with Children and/or Pets

Since king size mattresses are very popular, you can easily find them in nearly every mattress model. However, not every brand is going to offer some of the beds that are bigger than a king including the California king, Wyoming king, Texas king and Alaskain king. Keep that in mind if you are interested in a larger-than-life mattress. 

Since a king bed is one of the biggest beds available, they will be more expensive than a queen, full, and twin bed. Brands often have sales throughout the year, so you can score your dream king bed for a good deal if you shop around the big retail holidays.

How To Choose The Right Mattress Size

There are many factors that you should consider before determining what type of mattress is truly the best fit for you. You should keep in mind how your family may grow and change throughout the years and how your lifestyle and sleep preferences may evolve. 

Mattresses are made to last nearly a decade, so think about buying a new bed as an investment. Of course, a king bed is an expensive investment, so consider the following when making your purchase. 

Think About Your Bedroom Dimensions

You want to ensure a king size mattress will fit comfortably in your room before you purchase it. Your bedroom should be at least 12 feet long by 12 feet wide for a king size mattress to fit comfortably in it.

I cannot emphasize this enough: measure the size of your bedroom before making your purchase. Then, decide which furniture you want in your space, including the mattress. Preparing will help you avoid having an overcrowded bedroom.

Talk To Your Sleeping Partner 

If you’re part of a couple, your waking lives may be intertwined in beautiful, intricate ways, but it’s important to realize that not everyone has the same sleep style, patterns, and preferences. 

Brands offer mattresses made for specific body types, so you need to keep your partner in mind when considering a new mattress. That’s one reason why split king mattresses are so popular with couples, because each person can have a mattress that accommodates their body and sleeping preferences the best. 

You and your partner should both consider how big is your space and what furniture you require besides the mattress. That will help you both decide how much comfortable living space you ideally want in your bedroom. 

Also be sure to talk through firmness options, mattress types, and budget to be aligned as you make this decision together.

Establish Your Budget

Even though king size mattresses offer more space compared to other standard mattress sizes, you need to know that they usually come with pretty big price tags. 

You should be realistic about your budget and what you can afford. At the same time, you should balance that budget with the idea that a mattress is an investment, and one that could dramatically improve your life. 

On average, most king size mattresses can cost anywhere from $2,000 to $3,500 at full retail price. These prices will differ based on the brand and model. Many luxury mattresses are designed with premium features, which will hike the price of a mattress toward the top-end of that estimate. 

Beds created with all natural materials, cooling and support technology, and even beds made for people with back and joint pain will be more expensive compared to more traditional-feeling mattresses. Before deciding on which mattress to buy, you want to consider what features are important for you in a mattress. This will likely tell you how expensive a mattress will be.

Many brands offer sales throughout the year, oftentimes around major retail holidays like Black Friday and Memorial Day, so you can always shop those sales to save big bucks on a brand new mattress. We also have some exclusive mattress coupons to help save you some money as well. 

Consider Future Sleep Needs

Lastly, consider the possibility of how your sleep situation may change in the near future. 

If you’re living on your own as part of a couple, and will be cohabitating soon, you should consider your sleep partner’s needs. Say you’re thinking about getting a dog or a cat and imagining cuddling up with your furry friend, that’s another consideration to make. 

A mattress can last up to a decade, so you’re making a purchase that could impact your life for years to come. Just be sure to consider how your lifestyle or sleep preferences may change before diving headlong into a new mattress.

King Size Mattress FAQs

Do all King size mattresses have the same dimensions?

The majority of king mattresses are 76 inches wide and 80 inches long, but can differ slightly between brands. Just be sure to check the specs of the mattress you’re considering before finalizing the purchase. 

How much bigger is a King size mattress than a Queen size mattress?

A king mattress is 76 inches wide and 80 inches long.. A queen size mattress is typically 60 inches wide and 80 inches long. King and queen size mattresses are the same length, but a king is 16 inches wider. That may seem like a small difference, but it actually feels like a major impact.

What is the most popular bed size?

A queen size mattress is the most popular mattress size in the United States currently. Queen mattresses are so popular because they accommodate many different types of sleepers including single people, couples, and people who may share the bed with children or pets. 

Where should I shop for a King size mattress?

Since king size mattresses are very popular, shoppers shouldn’t have any issue finding them available at most online mattress stores as well as most in person furniture stores. However, it may be harder to find mattresses in stores that are larger than a king size bed. It is sometimes more difficult to find a mattress that is a Wymoning king, Texas king, and an Alaskan king in stores. Many people interested in those beds have to get them specifically made or look for them at specific retailers. 

Nichole Mondshein

Nichole Mondshein

Nichole is the Lead Reviewer for Sleepopolis. She covers everything from testing out mattresses to a variety of other sleep products in reviews, how-to guides, and more. You can also find her over on the Sleepopolis YouTube channel as well as our TikTok page. Nichole graduated cum laude from the University of North Carolina at Charlotte with a degree in Mass Media Communications, with triple minors in Journalism, American Studies and Women & Gender Studies.