Detailed Mattress Comparison

A king mattress is both longer and wider than a full-size mattress. A king-size mattress is 76 inches wide and 80 inches long, whereas a full-size mattress is 54 inches wide and 75 inches long. 

The king-size mattress is the largest while a full size mattress is towards the smaller sizes from among standard-size beds.

In the full bed vs king debate, note that these two mattress sizes were designed for two different needs. A full-size mattress offers more sleeping space for single adults or solo sleepers with pets, while a king is better suited for couples who prefer more space or share the bed with a pet.

To know about how to choose between a king and a full, there are several other considerations. We’ve curated all those for you to choose the best bed between a full size bed vs king bed. 

ParametersKing MattressFull Mattress
IN:76” x 80” x 11”
FT:6.33 X 6.67 X 0.92
CM:193.04 X 203.2 X 27.94
IN:54” x 75” x 11”
FT:4.5 X 6.25 X 0.92
CM:137.16 X 190.5 X 27.94
Bed Size76 X 80 inches54 × 75 inches
Recommended Room size13 × 13 feet9 × 9.6 feet
Comfortably Fits
  • Two adults with a pet or a child
  • Couples who like individual space
  • Single adult
  • Growing teens
  • Single adult with a pet or a child

What is a King Size Mattress?

A standard king mattress is 76 inches wide and 80 inches long. It is the same dimensions as two twin xl mattresses placed side by side. A king-size mattress is 5 inches longer and 22 inches wider than a full size mattress. 

A king size mattress is ideal for couples who have kids or would like the extra space to sprawl. King mattresses are also available in split king versions for couples who have different sleep preferences. 


  • Perfect for couples who enjoy more personal space or share the bed with kids
  • Ideal for spacious bedrooms
  • Easily available


  • Expensive 
  • Too wide for limited spaces
  • Hard to move because of weight 

What is a Full Size Mattress?

A full size mattress, also called a double bed, is 54 wide and 75 inches long. A full bed is 22 inches narrower and 5 inches shorter than a king bed and is the same length as a twin-size mattress. 

A full-size mattress is a popular mattress size because it can fit in compact spaces while offering a lot of sleeping space. It is a preferred mattress for single adult sleepers and for kids and teens as well. 


  • Ideal for teenagers and single adults
  • Easy to move 
  • A good option for smaller rooms or guest rooms


  • Too small for couples
  • Less legroom for tall sleepers

King vs Full Size Mattress: What should you consider before buying?

Room Size

For a king mattress, a bedroom that is at least 13 by 13 feet is recommended. Because it is larger than a full-size bed in both width and length, consider it for the larger rooms in your house. A full-size bed takes up less space than a king bed. If your room is 9 by 9.6 feet or 10 by 10 feet, go for a full size bed instead of a king bed. 

A king bed is ideal for larger rooms. It is smart to leave at least 2 feet between the bed and the walls for unrestricted movement and to make the room feel spacious.

Bed Size

A full bed is 54 inches wide and 75 inches long and fits full size mattresses that measure the same. A king mattress is better suited for beds that are 74 inches wide and 80 inches in length. The size and dimensions of a product can vary depending on the brand. So, take note of this before you go out and buy a mattress. 


A king bed is the better option for tall sleepers as it’s 5 inches longer than a full mattress. A king size mattress offers the extra length needed for tall individuals. It also offers more space for sleepers who like to stretch out at night. However, a full-size bed is shorter and tall sleepers may find the bed a little short to sleep comfortably in. 


You should expect to spend a little more on a king than on a full size mattress due to the size difference. The budget version of a standard king could be close to $1000, whereas a full-size mattress cost could be around $700. 


King and full mattresses are both standard mattress sizes so that you can find their accessories easily. Both king and full size mattresses can be accessorized with sheets, pillows, mattress protectors, or bed frames. Sheets for a mattress of king size cost more than full since they are larger in dimensions. However, the price gap is not very high. 

Also Read: Mattress Size Comparison Guide

More on Mattress Sizes

Choosing Between King vs Full 

If you are looking for a big bed for the master bedroom, a king-size bed is the best option. If you are looking for a supplementary bed or a bed in the children’s room or guest room, a full-size mattress is the better choice. Before making the correct decision, ensure that you read through the considerations above. 

Happy Buying!

How we compare to other Brands?

We offer a 365-day trial period and a warranty that lasts forever! If you don’t believe us go ahead and compare our offer to other brands. Apart from being one of the largest mattress sellers in the United States, we give you 9 reasons why nectar may be your best and the last mattress you purchase.

Sleep Trial Warranty Free Shipping * Free Return 2 Free Pillows Free Sheets Free Mattress Protector Price (Queen) Total Price
Nectar 365 Nights Forever Warranty™ check check check check check $799 $799 Shop Mattress
Casper 100 Nights 10 Years check check $178 $139 $95 $1,095 *$1,507+
Purple 100 Nights 10 Years check check $196 check $99 $1,149 *$1,444+
Shop Mattress *Price reflects the subtotal of mattress protector, sheets and two pillows (Single pillow for twin/twinxl) compared to the current promotion on Nectar. Additional shipping fees may apply in AK and HI. Price may not reflect any current promotions or discounts. Last Updated: Mar 2021.

Get upto $399 in Accessories Today

So long sleepless nights!


What is the difference between a king and queen size mattress?

The king mattress is 76 inches by 80 inches in dimensions. In comparison, the queen mattress is 60 inches by 80 inches. Both queen-size beds and king-size beds are of the same length but differ in width by 4 inches. 

Both beds are a great options for couples.

King XL vs full-size bed – which is better for couples?

Between king vs. full-size bed, a full mattress is preferable for single sleepers who don’t share their bed with anyone. The king bed is ideal for couples who like to sprawl at night.

How do I choose appropriate units of measurement to measure the bed?

The standard units of measurement are different for different geographies. For instance, the standard unit of measurement in the United States is inches. So, you can take both units of length and breadth as inches while you measure the dimensions of the bed you want to buy, and then measure space in your house to compare both these sizes. This will help you gauge what size bed will fit comfortably in the room.

How much bigger is a king than a full size mattress?

A king-size mattress is 5 inches longer and 22 inches wider than a full size mattress.