What is a Split King Mattress? (Pros, Cons, and Benefits)

A split king mattress has the same dimensions as a standard king-sized mattress, but is divided into two with a split down the middle so that each sleeper can customize their side of the bed. People choose to buy split king beds because they have different sleeping preferences from their partner and because the middle split reduces motion transfer.

What’s the difference between split king and king?

King vs. split-king: what’s the difference? The two types of mattresses have the exact same surface area, but they differ in one key aspect. A split-king mattress has a gap in the middle which separates the two sides of the bed. You can best think of a split king mattress as being two twin-XL mattresses combined into one.

The main benefits of split king mattresses are that they allow each sleeper to customize their side of the mattress (especially if you’re using an adjustable bed), they are easier to move and clean (since unlike a standard king they are technically two separate mattresses), and they reduce motion transfer.

Drawbacks of split kings are that they require you to buy specialized split king sheets (or use a combination of twin-XL sheets and king sheets), they don’t fit into small bedrooms, and that they are more expensive compared to a normal king-size bed or Cal king mattress.

What is a king-size mattress?

A king-size mattress measures 75 x 80 inches, making it the largest-sized bed available. California King mattresses have the same surface area but are shorter and wider. King mattresses are popular for couples who want more space for each sleeper. They can fit comfortably in most bedrooms (king beds are particularly popular in master bedrooms) with plenty of walking room and space for furniture. The next largest type of mattress is a queen-size, which is also made for two sleepers but offers much less space.

King mattress pros

Largest mattress size
More space for each sleeper
Great for large master bedrooms with plenty of walking space

King mattress cons

Not great for small bedrooms (less than 12 x 12)
Hard to move due to large size

What is a split-king bed?

A split-king size mattress has the same dimensions as a regular king mattress, but with a split in the middle. Each side of the split-king is equal in size to a twin-XL mattress. The benefit of split-king beds is that they allow each person to customize their side of the mattress to their own preferences. It’s the perfect mattress type for couples who have radically differing sleep preferences. For example, if one person is a back sleeper who prefers a firm mattress and the other is a side sleeper who requires a softer one, then a split mattress can give them the best of both worlds.

All of the best mattress brands offer a split-king version of their products. We highly recommend that you consider the split-king mattresses sold by Amerisleep and Idle Sleep. You can buy a memory foam mattress or latex mattresses – as well as most other mattress types – in split king configurations.

Split-king pros

Each side of the bed can be customized
Easier to move (compared to a standard king mattress or a California king bed) since it’s basically two twin-XL beds combined into one
Reduces motion transfer since each side is a separate mattress
Each side of the mattress can be adjusted independently when paired with an adjustable bed frame (one person can be sitting upright while the other lays flat)

Split-king cons

Requires specialized sheets: twin XL fitted sheets and a king-size top sheet. Custom split king sheet sets can be ordered online but are harder to find
Not great for small bedrooms (won’t leave any walking space)
The gap between the two sides of the mattress can be uncomfortable
More expensive when compared to king size bed or a California king

Other mattress sizes

If a split-king mattress is out of your price range or if you’re worried that you won’t have enough room for it in your bedroom, you might want to consider a different bed size.

Twin

Twin mattresses are designed for a single sleeper and are perfect for kids rooms or for adults who are sleeping in a small bedroom or studio apartment. Twin beds measure 38″ x 75″ – making them easy-to-move and affordable for most budgets.

Twin XL

Twin XL mattresses are the same width as standard twin beds, but they have an extra 5 inches of length. Twin XL beds are most commonly found in college dorm rooms and are also popular for teenagers, since the extra length accommodates taller people. Split king mattresses consist of two twin XL mattresses combined together.

Full

A full-sized mattress is about 16 inches wider than a twin XL bed. They are great for single sleepers who want extra room to spread out. They are also popular in guest rooms, since they don’t take up as much space as larger mattresses.

Queen

A queen-size mattress measures 60″ x 80″. They are a great choice for single adults who want more space and are also popular for couples since they can fit two sleepers on one bed. They provide more sleep space compared to a full-sized mattress but can still fit in a smaller bedroom.

California King

A California king mattress has the same surface area as a traditional king. The main difference is that California king beds are longer and narrower. The 72″ x 84″ size makes California king a popular size for taller couples. Split mattresses are also available in this size, although they aren’t as common as king mattresses. If you’re looking for a split Cal king mattress, we recommend that you buy a Saatva.

Frequently asked questions

Are two twin-XL mattresses the same as a king size?

Yes. The dimensions of a king size bed are the same as if you combined a twin-XL mattress side-by-side with another one.

When you buy a split king bed, you’re essentially getting two twin-XL beds with a split in the middle.

What kind of sheets do you put on a split king bed?

Finding the right set of sheets is usually the biggest inconvenience when it comes to buying a split king mattress. The best sheets that you can put on a split king are two twin XL fitted sheets combined with a king-size flat sheet and comforter.

There are some brands that make split-king sheet sets that have the correct fitted and flat sheets combined into one package, although they can be hard to find. Amerisleep Tencel sheets are your best option if you want to buy a sheet set for your split king bed.

How do you stop a split king from separating?

We recommend putting your split king mattress on an adjustable bed frame that has nonskid surfaces or side panels. This type of frame should prevent your split bed from separating in the middle.

You can also buy a bed strap with fasteners at each end for extra security. Attach one end to the underside of your new mattress and run it across the entire bed to the edge of the other half of the split-king. This will ensure that the two mattresses stay together.

Is a split-king adjustable bed worth it?

Adjustable bed frames are very expensive for all mattress sizes, and that’s especially true if you’re buying a split-king size frame.

Adjustable beds are great for your sleep health, since you can raise or lower your head and feet until you find the perfect position for your needs. When buying one for a split king, you can adjust each side independently so that you don’t have to compromise with your partner like you would when using standard king beds.

Depending on the model, some adjustable beds even have a massage feature. This means that you can be laying flat and enjoying a relaxing massage while your partner is sitting up and reading a book.

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Robert Pagano

Co-Founder at Sleepline

Robert is one of the two co-founders here at Sleepline.

He's been involved in the mattress industry for almost a decade and is dedicated to using his expertise to help you choose the right mattress.

Robert's main goal is to give you straightforward info on what works - and what doesn't - so you can spend less time stressing about sleep and more time living your life (that's what we're all here for, right?).