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

Twin XL mattresses are great for kids and solo sleepers—they offer plenty of legroom and enough space to get comfortable without feeling cramped. Since the dimensions of two twin XL…

Last Updated On December 1st, 2021
Twin XL vs. Split King: What’s the Difference?

Twin XL mattresses are great for kids and solo sleepers—they offer plenty of legroom and enough space to get comfortable without feeling cramped. Since the dimensions of two twin XL mattresses placed side by side equal that of a king, many mattress brands offer a split-king size.

Split-king size mattresses are two separate twin XL beds placed next to one another in a frame. These beds are perfect for couples with very different sleep needs, as this set-up allows each sleeper to customize their side of the bed.

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What Is a Twin XL Size?

Twin XL mattresses measure 38 inches by 80 inches, making them 5 inches longer than a standard twin. The extra length comes in handy to accommodate growing teenagers or taller adults. Twin XL sizes are common in children’s rooms, college dorms, guest rooms, and spare bedrooms.

Families with two or more children may benefit from bunk beds that fit twin XL mattresses—optimally utilizing space, leading to more play area.

A twin XL size is also a good option for those living in studio or small apartments where space is limited.


  • Suitable for growing teenagers and tall adults
  • Lightweight, easy to carry
  • Bunk bed compatible
  • Longer than a standard twin


  • Too small for couples
  • Not suitable for co-sleeping with pet or child

Prices of our Amerisleep Twin XL Size Mattresses

Amerisleep AS1$664
Amerisleep AS2$769
Amerisleep AS2 Hybrid$1049
Amerisleep AS3$839
Amerisleep AS3 Hybrid$1119
Amerisleep AS4$1049
Amerisleep AS5$1329
Amerisleep AS5 Hybrid$1609
Amerisleep Organica$1349

What Is a Split King Size?

A split king mattress is a standard king divided in half, allowing each sleeper 38 inches by 80 inches of personal space.  Split kings allow couples with different sleep styles to customize their side of the bed. If one sleeper wants a soft mattress while another prefers a firm, a split-king allows each sleeper to have their “best mattress.”

Twin XL vs. Split king

Split kings are also a popular option amongst those with adjustable bed frames because they allow couples to adjust each side of the base independently—one partner can sit up and read while the other drifts off to sleep in the zero-gravity position.

To make a king bed look uniform, you’ll need two twin XL fitted sheets and a king-size flat sheet. Split-king sheet sets are not as common, but you can typically purchase these from brands that carry split-king size mattresses.


  • Personalized comfort and support
  • Lightweight
  • Easy to maneuver


  • Expensive
  • Difficulty finding sheet sets

Prices of our Amerisleep Split King Size Mattresses

Mattress Price
AS2 Hybrid$2098
AS3 Hybrid$2238
AS5 Hybrid$3218

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Save $300 on the Amerisleep AS3 with our discount code
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How Does a Twin XL Size Relate to a Split King?

A standard king size mattress divided in half is two twin XL beds, measuring 38 inches by 80 inches—creating a split king bed. A split king is not a different size in itself, it’s two twin XLs placed side by side.

While twin XLs can be used only as single beds, split kings (two twin XLs) are the perfect mattresses for couples with different sleep needs.

Other Mattress Sizes

If a twin XL or split king mattress doesn’t suit you, check out other available sizes such as a twin, full, queen, king, or California king.

Twin Size

Measuring 38 inches by 74 inches, twin size mattresses are perfect for children, or single adults.

Twin beds are small in size, making them a convenient option where space is limited. Twin size mattresses are also bunk bed compatible. If you have two or more children, you can utilize space with a bunk bed.

Full or Double Size

A full or double bed is 16 inches wider than a twin and may accommodate an adult and a child. Measuring 54 inches by 75 inches, a full size mattress is commonly found in children’s rooms, guest rooms, college dorm rooms, or shared adult bedrooms. Though called a “double,” ironically, this size may be too small for couples.

Queen Size

Queen mattresses are the most popular amongst Americans because they suit single sleepers as well as couples. Measuring 60 inches by 80 inches, they are best for single adults offering them more room to stretch and sleep comfortably. However, a queen may be too small for some couples who prefer their personal space.

A queen size is perfect for single sleepers because they can stretch out and relax without the fear of rolling off the bed. If you are a single sleeper, with no constraint of space or budget, a queen may be a good fit for you.

King Size

Measuring 76 inches by 80 inches, the king size mattress is a perfect fit for couples. A traditional king is big enough to accommodate children—if they want to sleep with their parents on some nights. A king size bed, while suitable for larger master bedrooms, is expensive and heavy—maneuvering a king bed may be difficult due to its weight.

California King Size

A California king size mattress is 4 inches narrower and 4 inches longer than a king. Measuring 72 inches by 84 inches, a California king is the longest available standard size mattress—the extra length gives more legroom for tall people.

Mattress Dimensions Suitable to Room Sizes

An overcrowded bedroom may disturb your sleep. When buying a bed, factor in conditions like furniture and floor lamps, and leave enough room for walking space. We suggest leaving 2 feet of space on all three sides of your bed to provide a peaceful sleeping ambiance without feeling overcrowded.

Mattress Dimensions Bedroom Size


Do two twin XL beds make a California king mattress?

No, two twin XL beds will make a standard king mattress. Two twin XL mattresses placed side by side will measure 76 inches by 80 inches (size of a standard king), while a California king is 72 inches by 84 inches.

Do you need a box spring on an adjustable bed?

No. Box springs cannot bend like an adjustable base, so you cannot pair the two. Adjustable bed frames do not require box springs or foundations since they provide a solid, sturdy support for your mattress. Split king mattress can be kept directly on a split king adjustable bed frame for more personalized comfort. Adjustable bed bases can be elevated at the head and feet to better relieve pressure points.

Who needs a split king bed?

Split king beds are perfect for couples who have different sleep needs and prefer different mattress types. Partners may require a different combination of cushion and support for their comfort. They can have a latex, memory foam, innerspring or hybrid mattress on either side of the bed. To maintain a uniform look, it’s better if both the twin XL mattresses are of the same height.


When deciding on your mattress size, consider your sleeping style, whether you sleep alone or with a partner, and your budget. A twin XL size may suit a single sleeper, but for couples, a split king bed is perfect. A split king might be the better choice if you and your partner prefer different mattress types and have different sleep needs.

About the author

Mitchell Tollsen is a graduate student and a freelance writer who’s contributed to the Early Bird blog for three years. Mitchell’s always been fascinated by the science of sleep and the restorative processes our bodies undergo when at rest. The self-titled “Sleep Expert” is always looking for ways to improve his shut-eye, and throughout the years has implemented numerous lifestyle changes and tried dozens of sleep-promoting gadgets to determine the best ways to truly get better rest.

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