How Wide Is A King Sized Bed?

When you are purchasing a new bed, it is best to get an understanding of how big it's going to be before you buy it.

You don't want the bed and the mattress to arrive, only to find out that it takes up most of your bedroom and you now can't use the room for anything else.

Before you buy, measure out what you have space for and double check how wide your mattress is going to be. 

In this article, you will find everything you need to know about King Sized mattresses - including how big they are, who they're right for, and what the alternatives are. 

How Wide Is A King Sized Mattress

The dimensions of an American King Sized Mattress are as follows: 

76" x 80" 

Of all the mattresses, the King Sized mattress has the biggest surface area, although it is not the longest mattress.

This mattress would fit on a King Sized bed frame and might fit on a bed frame designed for a California King mattress. 

The first King Sized mattress was said to be created in 1890 - however, it was a lot bigger than the mattresses we are used to today.

That mattress had enough space for 15 people. 

Who Needs A King Sized Mattress

There are a few elements that you need to consider when buying a mattress:

  • Your size
  • Your height
  • Sleep position
  • How many people will be using the bed
  • Price
  • Space you want in the bed
  • Space available in your bedroom

A King Sized mattress is perfect for two adults who like to have a lot of room when they are sleeping. It has a total surface area of 6080 inches.

If you are an average height or less, a King Sized mattress will be perfect for you. 

If you have small children or pets that occasionally join you in bed, a King Sized mattress may be a good option for you.

What Is One Size Smaller Than King Sized?

A Queen Sized mattress is one size smaller than a King Sized. Its dimensions are as follows:

  • 60" x 80"

This mattress is the same length as a King Sized but it is not quite as wide. This is the most popular mattress size as it is easiest to fit into a normal sized bedroom.

It is best suited for adults of average height who like a little bit of space. But don't move around a lot in their sleep. 

This mattress has a surface area of 4800. 

What Is One Size Bigger Than A King Sized?

What Is One Size Bigger Than A King Sized?

When it comes to the surface area, the King Sized mattress is the biggest, however, the California King Sized Mattress is longer than the King and only 32 inches smaller overall.

The dimensions of the California King Sized mattress are as follows:

72" x 84"

As you can see, the California King is less wide than the traditional King, but is 4 inches longer. Its total surface area is 6048 inches (compared to 6080 for the King Sized). 

This is going to be a great option for two adults who are looking for a good amount of space, but one of them is taller than average.

California mattresses are slightly harder to get hold of, so they tend to be more expensive than traditional King mattresses, despite being slightly smaller. 

What Is The Smallest Mattress Size?

The smallest mattress is the Twin Sized mattress - this is designed for children rather than single adults.

The dimensions of the Twin Sized are as follows:

  • 38” X 75”

This mattress is 5 inches shorter than the King, Queen, and California King sized mattresses. This mattress has a surface area of 2080 inches.

Even people of average height might find this mattress a little short. These types of mattresses are best suited for children and teenagers. 

They take up the least amount of room and tend to be the cheapest mattress to buy. You may struggle to find memory foam mattresses in this size. 

Do Other Countries Use The Same Size System?

In years gone by, each country has used its own mattress sizing system. 

However, as production has become more globalized, so have mattress sizes. As it makes it much easier for manufacturers to make the mattresses in bulk.

In the last 20 years, the American sizing system has become the most popular and the one that is used around the world. 

A handful of countries use their own system. 

Mattress Size Chart

American sizes - 





38" X 75"

Twin XL

38" X 80"


54" X 74"


60" X 80"


76" X 80"

California King

72" X 84"

Frequently Asked Questions

Here are the questions we are asked most frequently about beds and the answers to them.

Is A King Sized Mattress The Biggest Mattress?

The King Sized Mattress has the biggest surface area of all mattresses - 6080 inches. But the California King is longer and has a surface area of 6048 inches.

How Often Should I Change My Mattress?

You should change your mattress at least once every 10 years but should change it earlier if it is no longer comfortable or your doctor recommends you do so.

If you injure your back then you may need to get a specialized mattress to support your spine.


The King sized mattress (76" x 80") is 76 inches wide and 80 inches long. It has a total surface area of 6080 inches.

Of all the mattress sizes, it is the widest and has the biggest surface area - but it is not the longest. Taller people will want to look into getting a California King Sized mattress.

A King Sized mattress will suit you well if you are two adults of average height, who like to have a lot of space when they sleep.

Before buying a King Sized bed, you should make sure you have enough space for it in your bedroom.