King vs. Split King: What’s the Difference?

By Sanchita Sen Certified Sleep Coach

Last Updated On April 11th, 2024
King vs. Split King: What’s the Difference?

Key Takeaways

  • King Size Mattress: King-size mattresses measure 75 inches by 80 inches and are the largest standard mattress size. They provide ample personal space, making them an excellent choice for couples with large master bedrooms. However, they may not be suitable for smaller bedrooms.
  • Split King Size Mattress: A split king mattress is the same size as a king-size bed but consists of two twin XL mattresses placed side by side. This configuration is ideal for couples with differing sleep preferences as it allows each sleeper to customize their side of the bed. Split kings are also compatible with adjustable beds and make it easier to move compared to a single large king mattress.
  • Choosing Between King and Split King Beds: The choice between a king and split king mattress depends on your bedroom size, whether you share your bed with a partner, and your sleep preferences. King mattresses are best for large master bedrooms, while split king mattresses are perfect for couples with different sleep needs and those who want to use adjustable bed frames.

Both king and split king are the largest standard mattress sizes on the market. Their wider size allows for more personal space, so couples don’t feel crowded. But which mattress should you choose? We share information on both sizes, including benefits and drawbacks.

What Is a King Size?

A king size mattress, or eastern king mattress measures 75 inches by 80 inches. King size mattresses are a great choice for couples and offers more personal space for both sleepers.

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Also known as Eastern king beds, these types of mattresses fit comfortably in a 12 feet by 12 feet bedroom, including a couple of nightstands with walking space.


  • Largest standard mattress size
  • More personal space
  • Best for large master bedrooms


  • Not ideal for bedrooms smaller than 12 feet by 12 feet
  • Difficult to move due to large size

What Is a Split King Size?

A split king mattress is the same size as a king-size bed, except it is two twin XL mattresses side by side instead of one uniform bed. Split kings are great mattresses for couples with differing sleep preferences, and they’re compatible with adjustable beds.

Split king mattresses allow sleepers to adjust the bed to their preference without disturbing the comfort of their sleep partner, unlike traditional king-size beds. If paired with a split king adjustable bed for couples, each partner can have their half in different configurations.

Plus, some companies offer customized split kings that allow couples to choose how firm or soft they want their bed to feel. A split king bed with two firmnesses is excellent for couples with very different sleep needs.

It’s smart to make sure each side of the split king bed has the same mattress thickness, though, for a more even look. Particularly when using a single bed frame for your split king.


  • Perfect for couples with differing sleep preferences
  • Easier to move—two smaller mattresses instead of one large bed
  • Isolates motion transfer


  • Separate fitted sheets
  • Too big for some bedrooms

Best Amerisleep King Mattresses

Quick Guide: A 30-Second Summary

Best King Mattress Overall Amerisleep AS3

Best King Size Mattress Overall

Amerisleep AS3

Amerisleep AS3 Mattress Image
  • Price Range: $1049 to $2198
  • Mattress Type: Memory Foam
  • Mattress Firmness: 5 to 6 out of 10 (Medium)
  • Mattress Thickness: 12 Inches
  • Available In: Twin, Twin XL, Full, Queen, King, California King, Split King
20 Years
Sleep Trial
100 Nights
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Pricing of Amerisleep King Mattresses

AS3 Hybrid$1699
AS5 Hybrid$2399
Amerisleep Organica$1599

Other Mattress Sizes

If you feel that a king or split king mattress isn’t the right size for you, other standard sizes include twin, twin XL, full, queen, California king, and split California king.

Twin Size

Twin size mattresses measure 38 inches by 75 inches and are the smallest standard mattress size on the market. Twin beds are great for children and for adults looking to save on space. For families with more than one child, bunk bed frames are a perfect space-saving option for multiple twin size mattresses in a single room.

Twin XL Size

Twin XL mattresses are 38 inches by 80 inches. They’re most common in college dorm rooms and great for tall people looking for more sleep space. Like twin mattresses, twin XL beds comfortably fit in smaller living spaces.

Full Size

Full-size mattresses are 54 inches by 75 inches. Full bed sizes are wonderful for teenagers and adults looking for more room to spread out. Full-size mattresses are also good for restless sleepers or those who switch between different sleeping positions at night.

Queen Size

A queen-size bed measures 60 inches by 80 inches. Queen mattresses are one of the best options for single adults and couples who like to sleep close to each other. They’re also great as guest beds.

California King Size

California king mattresses have similar mattress dimensions as king-size, but while a king-size bed is wider, a Cal king mattress is longer and more narrow at 72 inches by 84 inches.

Also known as “western king,” California king beds are a good option for taller individuals or couples who like to sleep closer together. The extra four inches allows those over 6 feet tall stretch out their feet comfortably.

Split California King Size

Split California king beds measure 72 inches by 84 inches. Like the standard king-size, California king is also available in split sizing, though they’re not as widely available as split king. A split California king bed has two halves, each 36 inches wide.

A split California king mattress is another great option for couples with different sleeping preferences and is also compatible with adjustable beds.

Choosing the Right Mattress Firmness

As we’ve said, the key advantage of a split king is that it allows sleepers to enjoy their preferred mattress firmness. Now, the importance of mattress firmness lies in its direct impact on sleep quality and overall well-being.

A mattress that aligns with an individual’s preferred sleeping position ensures proper spinal alignment, reducing the risk of waking up with aches and pains.

Side Sleepers

The best mattress for side sleepers is typically medium to soft. This level of firmness helps relieve pressure points at the shoulders and hips, providing optimal support and comfort. A mattress for side sleeping with some give allows the spine to align properly, reducing the risk of discomfort and promoting a restful night’s sleep for side sleepers.

Back Sleepers

Back sleepers generally benefit from a mattress with a medium-firm firmness. This level of support in a mattress for back sleeping helps maintain the natural curvature of the spine, preventing backaches. A balance between comfort and firmness ensures that back sleepers receive adequate support while enjoying a plush surface for a comfortable night’s sleep.

Stomach Sleepers

Stomach sleepers typically find a medium-firm to firm mattress most suitable. This firmness level helps prevent the lower back from sinking too deeply into the mattress, maintaining spinal alignment. A supportive surface in a mattress for stomach sleepers is crucial to prevent discomfort and potential long-term issues.

Combination Sleepers

Combo sleepers, who switch between different sleeping positions, often benefit from a medium to medium-firm mattress. This firmness level accommodates various sleeping styles, providing enough support for back and stomach sleeping while offering sufficient comfort for side sleeping. A versatile mattress for combination sleepers caters to their changing preferences throughout the night.

King vs Split King


Can you feel the gap in a split king?

While the presence of a gap in a split king mattress is inevitable, high-quality models often feature advanced designs to minimize the sensation of the gap. Some mattresses come with additional features like mattress connectors or straps to hold the two halves together securely, reducing the likelihood of feeling the gap.

Additionally, using a well-fitted mattress topper can help create a seamless surface, enhancing overall comfort and minimizing the impact of the division.

Is a split king bigger than a California king?

Yes, a split king is bigger than a California king because a standard king is bigger, if only by a small margin. While both standard kings and California king beds have the same perimeter, a standard king has a slightly larger surface area. A standard ing offers 6080 square inches, while a California king offers 6048 square inches.

Is a split king good for couples?

Yes, a split king can be an excellent choice for couples with different sleep preferences. Each side of the split king can be adjusted independently, allowing partners to customize their own sleep experience. This is particularly beneficial if one person prefers a firmer mattress while the other prefers a softer one.

Additionally, the split design minimizes motion transfer, ensuring that movements on one side of the bed are less likely to disturb the other person, promoting a more restful night’s sleep for both individuals.

How do you keep a split king from sliding apart?

To prevent a split king from sliding apart, consider using a non-slip mattress pad or grip underneath each mattress. Additionally, some manufacturers offer special straps or connectors designed specifically for split king mattresses, securing the two halves together.

Regularly inspecting and adjusting the connectors or straps will help maintain the alignment of the two mattresses over time. A tight king-size fitted sheet can also keep the two halves together, those this is not suitable for a split king adjustable bed that needs to move at different angles.

Can you put 2 twin beds together to make a king?

Yes and no. You can’t put two standard twin beds together to create a king-size bed. Two twin beds will make a mattress that is five inches shorter than a king bed. With some creativity you may be able to overcome that, using foam and thick headboards for example, but it will not be true king.

However, by aligning two twin XL mattresses side by side, you achieve the dimensions of a standard king mattress. It’s essential to use a king-size bed frame and mattress connector to secure the two twin XL beds together seamlessly.

What is the point of a split king?

A split king offers personalized comfort and accommodation for couples with varying sleep preferences. The bed consists of two separate twin XL mattresses, allowing each person to adjust their side independently.

Having a separate twin XL mattress is beneficial for partners with differences in mattress firmness, elevation, or other sleep preferences. Additionally, a split king minimizes motion transfer, reducing disturbances caused by one person’s movements for a more peaceful and undisturbed night’s sleep.

What is the disadvantage of split king?

One notable disadvantage of a split king is the presence of a gap or seam in the center, which may be felt by some individuals. While advancements in mattress design aim to minimize this gap, it can still be a concern for those who prefer a completely seamless sleeping surface.

Additionally, finding bedding that fits a split king properly can be challenging, as standard king-size sheets may not fully accommodate the two separate mattresses. Users need to consider these factors and weigh the benefits against potential drawbacks when choosing a split king mattress.

Which Size Is Right For You?

No matter which size you choose, the best mattress size will comfortably fit the bedroom with walking space and areas for furniture for aesthetic appeal. A king-size is a great option with its wider dimension, offering more personal space for couples.

A split king size is another great option, providing catered sleeping preferences so both couples have optimal comfort without compromise. Both a king and a split king mattress measure 76 inches by 80 inches and fit in a king bed frame. They are excellent choices for any master bedroom.

About the author

Sanchita Sen is a full-time writer focusing on the sleep health and mattress industry. She is a former journalist who has written numerous articles on the healthcare sector. Some of the topics she has covered include how to lucid dream, fever dreams, melatonin for sleep, and best gel memory foam mattress. Sanchita holds a Master of Arts in Communications from Convergence Institute of Mass Media and Information Technology Studies. She is also a published author, who seeks inspiration from both real life and the world of fiction.

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