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

A king size mattress offers couples plenty of personal space, and split king mattresses let couples customize their bed. The main difference between the two is that a king bed is one mattress, while a split king bed is two mattresses pushed together. If you’re looking to upgrade your master bedroom, you might wonder which is the best mattress for you—the regular king mattress, or a split king mattress?

What is a King Size Mattress?

A king size mattress, also known as an eastern king, is the widest standard bed size. It’s 76 inches by 80 inches, ideal for couples who want space to spread out. A king mattress fits best in a master bedroom that’s at least 12 feet by 12 feet, to leave enough walking space and room for nightstands and dressers.

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Pros of a King Mattress

• At 6080 square inches, a king size mattress offers couples plenty of personal space. There’s even enough room to co-sleep with a child.
• King mattresses are compatible with adjustable bed bases. However, you must set up the base to move the mattress as a whole— otherwise the base will try to move each half independently.

Cons of a King Mattress

• It’s difficult to move because of its size and weight—some king mattresses weigh close to 200 pounds!
• A king size mattress is not meant for an average-size bedroom. If you place it in a bedroom smaller than 12 feet by 12 feet, you may feel cramped and claustrophobic.

What is a Split King Size Mattress?

A split king mattress is a king size mattress split in half, with each side equal to a twin XL size mattress. Split king mattresses let couples personalize their side of the bed to their preferences, preventing sleep disturbances. If one partner is a side sleeper who needs a soft mattress and the other a stomach sleeper who needs a firm mattress, a split king lets them prioritize their sleep health while still sharing a bed.

Pros of a Split King Mattress

• Split king mattresses accommodate each partner’s sleep needs.
• A split king mattress is easier to move than a king mattress since it’s essentially two twin XL beds.
• Split king mattresses eliminate motion transfer because each partner has a separate mattress.
• Each half of a split king mattress moves separately on an adjustable bed frame. One partner can sit up and read, while the other relaxes lying down.

Cons of a Split King Mattress

• Split king mattresses need specialized bed sheets—twin XL fitted sheets and a king size cover sheet. Split king sheet sets exist, but they are easier to find online than in stores.
• Like a standard king mattress, split king mattresses fit best in bedrooms that are 12 feet by 12 feet.
• The halves of split king mattress can’t interlock, leaving a noticeable line between the two. This gap may cause discomfort if you or a partner tend to roll toward the middle.
• Split king mattresses sometimes cost a little bit more than a regular king mattress, although the prices are still comparable.

Other Mattress Sizes

Perhaps a king size mattress is too big for your bedroom, or too costly for your budget. You could consider another mattress size, such as a queen size mattress.

Twin

A twin size mattress is the smallest standard bed size, perfect for kids’ rooms and single sleepers short on living space.  If you have two children sharing a room, consider a bunk bed with a pair of twin mattresses. A twin bed also offers guests a comfortable night’s sleep without taking up too much space.

Twin XL

A twin XL size mattress is 5 inches longer than a regular twin. You might want to consider giving your child the extra space of a twin XL mattress to grow into after they’ve graduated from cribs and toddler beds. A twin XL mattress is also standard in most college dormitories—students can bring their bed and later use it in their first apartment.

Full

A full size mattress, sometimes called a double bed, is 16 inches wider than a twin size mattress. The extra width offers single sleepers more room to spread out. A full mattress fits well in a studio apartment, children’s room, or guest bedroom.

Queen

A queen size mattress is the most popular mattress size because it’s suitable for almost anyone. It’s great for couples and single sleepers who want the room to spread out. A queen mattress fits in an average bedroom or a master bedroom. If you have a spacious guest room, a queen mattress is a perfect bed for visitors.

Like a king bed, queens are also available as split mattresses—each half is 30 inches wide and 80 inches long.

Cal King

A California king size mattress, or a western king, is 4 inches longer a traditional king, with the tradeoff that it’s also 4 inches narrower. If you’re more than 6 feet tall or share a bed with a tall person, a Cal king mattress might be the perfect mattress.

You can find split versions of Cal king mattresses if you and your partner have different sleep needs. Each half of a split Cal king mattress is 36 inches by 84 inches.

More Buying Considerations

Material Type

You have four different mattress types to look at when shopping.

Memory foam mattresses feature excellent pressure relief and motion isolation. Memory foam can retain too much heat, which is why many manufacturers add gels or other cooling materials.

Latex mattresses, like memory foam beds, can relieve pressure. However, natural latex is made from rubber tree sap, making it a more eco-friendly material than memory foam. Latex mattresses are some of the more expensive beds available.

Innerspring mattresses contain steel coils, with padding to provide a comfortable sleeping surface. Some people, particularly side sleepers, find innerspring mattresses don’t provide enough pressure relief.

Hybrid mattresses pair innerspring coils with a 2 or 3-inch foam layer for greater comfort. The foam layer offers pressure relief, while the coils promote airflow.

Firmness

Your body weight and sleeping position affect what firmness level is right for you.

A mattress for side sleeping should have a soft to medium feel.

The best mattresses for back sleepers are medium-firm to firm.

A stomach sleeper’s mattress should be firm. However, we recommend stomach sleepers switch to side sleeping or back sleeping because stomach sleeping overextends the spine and causes back pain.

A mattress for a heavy person over 230 pounds should have a firmer feel. A mattress for a petite person under 130 pounds should have a softer feel.

If you need a mattress for back pain, look for one with a medium-firm feel. Studies have found a medium-firm feel promotes a neutral spine alignment.

Did We Help?

A standard king and a split king mattress are both excellent choices for any master bedroom and are usually both options in an adjustable bed and mattress combo, for couples who seek maximum comfort. The best mattress size for you depends mostly on you and your partner’s sleeping preferences.

Can the two of you compromise with a medium-feel king mattress, or do you need a customized split king to sleep soundly? The answer will lead to a better night’s sleep for both of you.