Key Takeaways
  • The king size mattress is the widest standard size mattress available, and the California king is the longest. Both options are excellent for couples and those who want more space. However, owning a king or California king requires a higher budget and a bigger bedroom than a smaller mattress does.

A king size mattress can offer you more space, but deciding whether it’s the right size for you will depend on your needs and sleep habits. We’ll explain everything you should know about shopping for and purchasing a king size mattress, from how much floor space is required to what kind of budget you’ll need. 

We’ll also discuss the major differences between standard king size mattresses and California king beds. Although they are similar, these two models have slightly different measurements, making each one better suited to certain types of sleepers. We’ll help you determine which one best fits your sleep environment so you can choose the best mattress for you. 

The Dimensions of a King Size Bed

King size beds measure 76 inches wide by 80 inches long. They are the widest standard mattress size available, though some companies do manufacture oversize and custom beds that are wider. While king size dimensions are generally standardized, exact measurements can vary slightly between mattress companies. 

A king size bed is an excellent choice for couples looking for space to spread out, as well as people who sleep with their children or pets. Single sleepers may also enjoy the spaciousness of a king mattress. 

Keep in mind that king size beds have a surface area of 6,080 square inches, which means they have more surface area than other mattress sizes. You’ll need a significant amount of floor space to ensure there’s enough room for a mattress this size. 

Mattress Sizes

In the U.S., the six most common mattress sizes are twin, twin XL, full, queen, king, and California king. If you purchase a standard size mattress, it’s much easier to find bed frames, sheets, and other sleep accessories than it is if you have a bespoke or unusual mattress size. 

Since there are so many companies that make mattresses, you may notice slight differences among models that claim to be the same size. However, manufacturers generally try to adhere to each size’s specific dimensions to ensure that their mattresses are compatible with bedding, foundations, and other products that are made for each size.   

Mattress SizeDimensions (Width x Length)
Twin38” x 75”
Twin XL38” x 80”
Full 54” x 74”
Queen60” x 80”
King76” x 80”
California King72” x 84”

King vs. California King Beds

King and California king size beds are large mattresses that cater to different needs. The California king is narrower and longer than the standard king, so it’s best for tall sleepers and those who prefer a mattress with extended length. A California king measures 72 inches wide by 84 inches long while a regular king is 76 inches wide by 80 inches long. 

The surface areas of both mattresses are very similar, and each option is large enough to comfortably fit two people. When deciding between them, consider the heights of each sleeper as well as their preferred sleeping position. 

If you tend to sprawl out width-wise, a regular king is likely the best option. However, if you sleep with your legs extended and arms close to your sides, you may prefer the California king’s above-average length. Regardless of which mattress you choose, you’ll need to ensure you have adequate bedroom space and a budget to accommodate the more expensive bedding that these models require. 

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How to Choose a Mattress Size 

Choosing the best mattress size for you involves taking a few factors into consideration. King size mattresses give you more room to spread out, but they are also more expensive than other sizes. Before committing to a king size mattress, it’s important to get clear on your specific needs. 


While there are standard mattress dimensions when it comes to length and width, the same can’t be said for height. Companies make mattresses in a wide variety of profiles to suit the preferences of many different kinds of sleepers. Though there are exceptions, most mattresses are between 6 and 18 inches tall, with the majority measuring between 10 and 15 inches in height. 

When purchasing a mattress, you need to consider both the available floor space and the room’s height. If you intend to use a king mattress with an RV, bunk bed, or in other situations where space is limited, make sure you choose a model with a profile that fits. 

Sleep Position

Each sleeping position takes up a different amount of space on a mattress. Side sleepers who curl up need more width than they do height so that they can bend their knees or extend their arms. In contrast, both back and stomach sleepers need enough length to ensure that their feet don’t hang off the edge of the bed.

Active sleepers and people who switch positions throughout the night should choose a mattress that’s both wide and long enough for their most common postures. A California king mattress may be best for those who prefer additional length, while a standard king could be better for people who need lots of space across the width of the bed. 

Bedroom Size

King size beds require significant space. Some bedrooms may not have enough square footage for a king size bed. In addition to the size of the mattress itself, you’ll also need to think about how much room your bed frame takes up and whether you’ll be able to walk on either side of the bed. Make sure to factor in any other furniture when measuring the available space in your room. You should also make sure your bedroom door frame is wide and tall enough for you to get the mattress into the room. 


Generally, king size mattresses are more expensive than those with smaller dimensions. Making a mattress this size requires more materials and added labor time, which increases the overall cost. King size bedding and accessories also use more materials, which is often reflected in their prices. Expect to pay more overall for king size mattresses, bedding, frames, and other necessities. 

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