When choosing a mattress, understanding the dimensions is crucial for ensuring comfort and compatibility with your bedroom space. A king size mattress is often seen as the epitome of luxury, offering ample space for couples and those who value room to stretch out. This comprehensive guide will delve into the exact measurements of king size mattresses, including the standard king, California king, and other variations, to help you make an informed decision.

What Size is a King Size Mattress?

A king size mattress is a popular choice for couples and those who enjoy a spacious sleeping area. Here are the standard dimensions for a king size mattress:

Standard King Size Mattress

  • Width: 76 inches (193 cm)
  • Length: 80 inches (203 cm)

California King Size Mattress

In addition to the standard king, there is also the California king, which is slightly different in its dimensions:

  • Width: 72 inches (183 cm)
  • Length: 84 inches (213 cm)

Key Considerations

When choosing a king size mattress, consider the following factors:

Room Size

Ensure your bedroom is large enough to accommodate a king size mattress comfortably. A room that is at least 12 feet by 12 feet is generally recommended.

Bed Frame Compatibility

Check that your bed frame or base can support the dimensions of a king size mattress.


King size bedding, including sheets, duvets, and blankets, must match the mattress dimensions to fit properly.


Consider the size and layout of your home. Make sure the mattress can be easily delivered to and moved within your space.

What Size is a King Size Mattress?
Photo Credit: casper.com

Standard King Size Mattress

Exact Dimensions

A standard king size mattress measures 76 inches wide by 80 inches long (193 cm by 203 cm). This generous size provides ample space for two adults to sleep comfortably, with plenty of room to move without disturbing each other.

Common Uses

The standard king size mattress is ideal for master bedrooms, offering luxurious space for couples. It’s also a great choice for families who enjoy co-sleeping with young children or pets. The expansive size ensures everyone has enough room to sleep soundly.

California King Size Mattress


A California king size mattress, often referred to as the “Cal king,” measures 72 inches wide by 84 inches long (183 cm by 213 cm). While it is narrower than the standard king, it offers additional length, making it perfect for taller individuals.

Differences from Standard King

The main difference between a standard king and a California king is the dimensions. The California king is 4 inches narrower but 4 inches longer than the standard king. This makes it a better fit for taller sleepers who need extra legroom.

Other King Size Variations

Split King Dimensions

A split king mattress consists of two twin XL mattresses, each measuring 38 inches wide by 80 inches long (97 cm by 203 cm). Combined, they form a standard king size but offer the flexibility of individualized firmness and adjustable bases, catering to couples with different sleeping preferences.

Custom King Sizes

Custom king sizes are available for those with unique needs or specific room dimensions. These can vary in both width and length, and are often used in large or unusually shaped bedrooms where standard sizes might not fit optimally.

Choosing the Right King Size Mattress

Room Size Considerations

Before purchasing a king size mattress, measure your bedroom to ensure it can accommodate the mattress comfortably. A king size bed requires a room that is at least 12 feet by 12 feet to allow for additional furniture and movement space around the bed.

Sleeping Preferences

Consider your sleeping preferences and habits. If you prefer more space to spread out or if you sleep with a partner and value personal space, a king size mattress is an excellent choice. Taller individuals may prefer the extra length of a California king.

Benefits of a King Size Mattress

Comfort and Space

One of the primary benefits of a king size mattress is the comfort and space it provides. The larger sleeping area allows for more restful sleep, especially for those who move around frequently during the night.

Ideal for Couples

For couples, a king size mattress offers the perfect balance of closeness and personal space. Each person has enough room to sleep comfortably without disturbing the other, leading to a more peaceful night’s sleep.

Comparing King Size to Other Sizes

King vs. Queen

A queen size mattress measures 60 inches wide by 80 inches long (152 cm by 203 cm), making it smaller than a king. While a queen-size is suitable for couples, it does not offer as much personal space as a king size mattress.

King vs. Full

A full size mattress, also known as a double, measures 54 inches wide by 75 inches long (137 cm by 191 cm). It is significantly smaller than a king size and is typically used for single sleepers or smaller guest rooms.

Materials and Types of King Mattresses

Memory Foam

Memory foam mattresses conform to the shape of your body, providing excellent support and pressure relief. They are available in king size and are ideal for those who prefer a softer, contouring feel. Here is an example: Zinus 10 Inch Green Tea Cooling Memory Foam Mattress Review


Innerspring mattresses feature coils that provide traditional bounce and support. They are a popular choice for king size mattresses, offering durability and a firmer feel.


Hybrid mattresses combine the benefits of memory foam and innerspring coils. They provide a balance of comfort, support, and motion isolation, making them a versatile choice for a king size mattress.

Maintaining Your King Size Mattress

Proper Support

Ensure your king size mattress has proper support to maintain its shape and longevity. Use a sturdy bed frame with a center support bar or a box spring designed for king size mattresses.

Regular Cleaning

Regular cleaning is essential to maintain the hygiene and lifespan of your mattress. Vacuum the mattress surface to remove dust and allergens, and spot clean any stains with a mild detergent and water.

Where to Buy a King Size Mattress

Online Retailers

Many online retailers offer a wide selection of king size mattresses, often at competitive prices. Websites like Amazon, Wayfair, and specialty mattress companies provide detailed product descriptions and customer reviews to help you make an informed decision.

In-Store Options

Visiting a mattress store allows you to try out different king size mattresses before purchasing. Retailers like Mattress Firm, Macy’s, and local mattress stores provide the opportunity to test the comfort and support of various options.

Cost Considerations

Price Range

King size mattresses vary in price depending on the materials and brand. They typically range from $500 to $5000. Higher-end mattresses with advanced features and premium materials will be at the upper end of this spectrum.

Additional Costs

Consider additional costs such as delivery fees, bed frames, and mattress protectors. Some retailers offer free delivery and setup, which can be a significant cost-saving advantage.


What are the exact dimensions of a king size mattress?

A standard king size mattress measures 76 inches wide by 80 inches long (193 cm by 203 cm).

How does a California king differ from a standard king?

A California king is 72 inches wide by 84 inches long (183 cm by 213 cm), making it 4 inches narrower and 4 inches longer than a standard king.

Can a king size mattress fit in any bedroom?

A king size mattress requires a room that is at least 12 feet by 12 feet to fit comfortably with additional furniture and space to move around.

What types of mattresses are available in king size?

King size mattresses are available in various types, including memory foam, innerspring, and hybrid models.

How do I maintain a king size mattress?

Maintain your king size mattress by providing proper support, regularly cleaning it, and rotating it periodically to ensure even wear.

Where can I buy a king size mattress?

King size mattresses can be purchased from online retailers like Amazon and Wayfair, as well as in-store at places like Mattress Firm and Macy’s.

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