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King vs. Split King Mattress: Which Mattress Size is Right for You?

King vs. Split King Mattress: Which Mattress Size is Right for You?

Mattress Guides
Read Time: 2 minutes
  • The primary difference between a king and a split king lies in their construction, with king mattresses being a single unit and split kings being two beds pushed together. Both share the same dimensions and price, catering to different needs.
  • King mattresses are ideal for couples with similar firmness preferences, offering ample space for comfortable sleep. They work well for co-sleeping families and fit large master bedrooms. Additionally, king beds are compatible with adjustable frames, promoting health benefits such as reduced back pain and improved circulation.
  • Split king mattresses are designed for couples with different firmness preferences. They allow each person to choose a mattress suitable for their needs, addressing issues like motion transfer. Split kings are also compatible with split adjustable bed frames, offering individualized comfort.

The biggest standard mattress sizes—the king and split king—are the same size and price, but the primary variation between these two mattresses is their construction. King mattresses are one single bed, while split king mattresses are two beds pushed together, equaling the size of a king.

Our guide explains the similarities and differences between kings and split kings so you can determine which will work better for you and your home.

What is a King Size Mattress?

King mattresses, also called Eastern kings, are the widest standard bed. They measure 76 inches wide by 80 inches long and have 6080 square inches of surface area.

These beds are a great option for couples who have similar firmness preferences and want lots of space to spread out. Individual adult sleepers who have lots of space and want a luxurious bed can also use a king bed, but they don’t necessarily need one.

King size bed frames and accessories can get quite expensive due to how big they are, typically costing between $700 to $4000. Your bedroom should be at least 12 by 12 feet to accommodate a king bed so you still have space to walk around and fit other furniture in the room. It’s unlikely a king bed will fit in a small space, such as studio apartments.

Best King Size Mattress: Amerisleep AS3

  • Price Range

    See Price

  • Mattress Type

    Memory Foam

  • Thickness

    12 Inches

  • Firmness

    5 to 6 out of 10 (Medium)

  • Warranty

    20 Years

  • Sleep Trial

    100 Nights

Mattress Highlights
  • Bio-Pur® cools and comforts all kinds of sleepers
  • HIVE® for targeted support to different body areas
  • Bio-Core® offers tons of support & a long lifespan
Recommended For
  • Side, back, and combination sleepers
  • Couples
  • Hot sleepers

If you’re looking to share a bed with your partner without having to deal with the extra expense of a split king, the AS3 by Amerisleep might just be for you. This medium-feel mattress is so versatile it can handle most sleep styles and body types. That means you and your partner can share a bed and still get your sleep needs met.

The AS3’s medium feel isn’t only great for couples. It’s also fantastic for combination sleepers. Combo sleepers love to switch things up night after night. Sometimes they might sleep on their sides. Other times they might sleep on their backs. The amazing thing about the AS3 is you can be equally comfortable in both positions.

The AS3 doesn’t only have its medium feel to brag about, though. It also boasts Amerisleep’s proprietary Bio-Pur® foam. This memory foam contains plant oils in lieu of some petroleum products. Having plant-based ingredients gives this mattress several key advantages over regular memory foam.

Eco-conscious sleepers will appreciate the fact that this mattress contains fewer synthetic materials. Thus, it produces less toxic waste than traditional memory foam manufacturing. More natural ingredients are also better for those with chemical sensitivities. More natural ingredients mean less off-gassing from your new mattress.

Hot sleepers will enjoy the AS3’s cool-to-the-touch feel. The highly breathable Bio-Pur® foam keeps cool air flowing around your body. That translates into superior temperature regulation. It also works with the Refresh Cover to diffuse heat at the same time it’s bringing cooler air towards you.

Finally, active sleepers will love the responsiveness of the Bio-Pur® foam. Traditional memory foam can take forever to regain its shape when you move. But the plant-based Bio-Pur® foam pops right back into place.

Underneath the comfort layer, the AS3 sports a HIVE® transition layer for targeted pressure relief. Each section of the HIVE® layer corresponds to a different area of your body to offer it its ideal balance of support and cradling. So you will get more lift under your head and feet. And you’ll feel more cushioning under your hips and shoulders.

The final layer of the AS3 is the ultra-dense Bio-Core® support layer. This high-density foam not only keeps your spine supported and your body lifted onto the sleeping surface. It also extends the life expectancy of this mattress to 20 years.


  • Medium feel makes this mattress versatile enough for most sleep styles and body types
  • Targeted support and pressure relief offer optimal spine alignment and prevent pain
  • Highly responsive and breathable plant-based foam is perfect for active and hot sleepers alike.

Current Promotion

$300 Off All Mattresses


Benefits of Choosing a King

Many people enjoy king beds for the amount of space there is to stretch out. They work well for couples, co-sleeping families, and large bedrooms.

Large Enough for Couples

King vs. Split King Mattress

While queen mattresses are a common option for couples, king mattresses offer much more personal space and are more comfortable in the long-term. For couples who both enjoy stretching out, king mattresses are a great option.

Works for Co-Sleeping Families

Families who enjoy co-sleeping or cuddling in bed with their child might prefer a king mattress so they can comfortably sleep together. With this in mind, king mattresses are only big enough to fit two adults and one small child at most.

Suits Large Master Bedrooms

If your bedroom is 12 feet by 12 feet or bigger, a king mattress can make for a great focal point in the center of the room.

Compatible with Adjustable Bed Frames

King beds—and other standard mattress sizes—are compatible with high-quality adjustable bed bases, motorized bed frames that allow you to elevate the top and foot of the bed to any angle you prefer. Adjustable bed frames are not only comfortable, but they have many health benefits, including reducing back pain, reducing sleep apnea symptoms, and improving circulation.

What is a Split King Size Mattress?

Split king beds have the same dimensions as a standard king, only the mattresses are split into two separate beds rather than being one single unit. The two mattresses are the equivalent of a twin XL size mattress, at 38 by 80 inches each.

Split kings are one of the best mattresses for couples with different firmness preferences and who want a split adjustable base. However, split king beds aren’t necessary for single adults since their main function is to suit couples.

One of the main drawbacks with the separate mattresses is there’s a noticeable gap between the two beds. So, if you and your partner ever decide to sleep closer together, the gap may make that uncomfortable. However, a king size mattress topper can smooth this out, covering up the gap.

Since a split king and an Eastern king bed share the same dimensions, they fit in the same sized bedrooms. Split kings and regular kings are usually about the same prices as well, though some brands might charge an extra hundred dollars or so for a split king.

Best Split King Mattress: Zoma Mattress

  • Price Range

    See Price

  • Mattress Type

    Memory Foam

  • Thickness

    12 Inches

  • Firmness

    5 to 6 out of 10 (Medium)

  • Warranty

    10 Years

  • Sleep Trial

    100 Nights

Mattress Highlights
  • AirCloth cover and gel memory foam for coolness
  • Medium feel provides the perfect balance
  • ReactivTM transition foam for active sleepers
Recommended For
  • Physically active people
  • Most sleeping styles
  • Hot sleepers

The Zoma Sports Mattress is a fantastic option for the firmer side of the bed for couples looking to do a split king. This medium-firm offering is perfect for back sleepers and heavier sleepers alike. It offers tons of lift and support without sacrificing pressure relief.

On top, the Zoma features a ventilated AirCloth cover to help keep air circulating around your body. This cover works with the ventilated gel memory foam to draw heat away from you while circulating cool air into the mattress at the same time. Thus, the Zoma offers two different cooling technologies that work in harmony with each other.

The gel memory foam also features the TriangulexTM zoned pressure relief system. This system offers tri-zoned relief targeting your:

  • Head and shoulders
  • Hips and lumbar region
  • Feet and knees

This targeted cushioning ensures that each area of your body has its unique pressure relief needs met.

Underneath the gel memory foam, you’ll find the ReactivTM transition layer. This unique material was designed to put the bounce back in your bed. While memory foam alone has a very slow response time, memory foam with the ReactivTM transition layer under it will bounce back right away. This is a feature you really need if you’re an active sleeper who likes to toss and turn.

The ReactivTM layer doesn’t just make your mattress bounce back. It also has the added benefit of protecting your body from pressure exerted by the high-density support core. And it keeps you lifted onto the sleeping surface.

Speaking of the support core, the Zoma’s Support+ base layer offers perfect spine-aligning lift. This will ensure you’re protected from back pain all night long. It also prevents sagging and soft spot development in the mattress for a full 10 years.

You might think a mattress with this many features would cost a fortune. However, one of the best things about the Zoma is its affordability. You can get your half of your split king for less than $600.

Plus, Zoma offers a highly affordable adjustable bed that can be bundled with the Zoma Mattress. Pairing the Zoma Adjustable Bed with your split king mattress lets each half of the mattress be set up in a unique position, excellent for couples where each partner wants something different from an adjustable frame.


  • Perforated gel memory foam pulls heat away from your body to keep you cool
  • Base layer provides optimal support and spinal alignment
  • TriangulexTM system offers targeted pressure relief to different areas of the body

Current Promotion

$150 Off All Mattreses


Benefits of Choosing a Split King

Split kings are great for couples since they can share a bed while also enjoying personal space. Plus, they can each choose a mattress suitable for their body types.

Helpful for Couples With Different Sleeping Styles

One of the primary benefits of a split bed is that they suit couples who are entirely different sizes with different sleep styles.

Say you weigh less than 130 pounds and are a side sleeper, but your partner weighs over 230 pounds and is a stomach sleeper. If so, you would both need very different mattress types to be comfortable. With a split king bed, you could have a soft mattress while your partner has a firm mattress, all while still sleeping close together.

Pairs with Split Adjustable Bed Frames

A luxurious accessory for split king mattresses is a split adjustable frame. Like standard adjustable frames, you can elevate your head and feet, but with a split king adjustable bed, both halves of the frame move independently. This way, you can adjust your bed without disturbing your partner.

Eliminates Motion Transfer

Motion transfer is a common issue for couples sharing a bed. When your partner gets in and out of bed or switches positions, their movements can transfer to your side of the bed, potentially disrupting your sleep or throwing you out of your comfortable position. Having two separate mattresses eliminates this issue, as one mattress’s movements won’t impact the other’s.

Easy to Transport

With a split king mattress, you’re working with two small mattresses versus one huge one. Twin XL mattresses are much lighter and thinner than king mattresses, so they fit through doors and even in some pick-up trucks. If you ever move homes or choose to rearrange your bedroom, you can transport the individual mattresses without difficulty.

Similar Mattress Sizes

If a king and divided king don’t seem to fit the bill, what are your other options? Some similar mattress sizes to a king or split king bed include a queen, California king, and a split California king mattress.

Queen Size

Queen mattresses are 60 inches wide and 80 inches long and are the most popular mattress option for single adults. Queen beds also work well for couples who have a small master bedroom or enjoy sleeping close together. A queen size mattress is also a good size for guest rooms.

Since queen mattresses are smaller than kings and split kings, they’re more budget-friendly.

California King Size

A California king size mattress is 72 inches wide by 84 inches long, making it 4 inches longer than standard kings, but also 4 inches narrower. People mistakenly assume Cal kings are bigger than kings, but they have a smaller surface area of 6048 square inches. We recommend getting a Cal king mattress if you’re a taller individual or have a narrow and long bedroom.

Split California King Size

Similar to the king mattress, California king mattresses come in a split variation. Although split California king mattresses are not as common as split king mattresses, they are a good option for tall couples with different firmness needs. You can also find split California king adjustable bases, but again, they are uncommon.


Is a king mattress the same size as two twins?

No, king and split king mattresses are the same as two twin XL mattresses side by side. Conversely, two standard twin size mattresses pushed together are 76 by 75 inches, which is 5 inches shorter than a king bed.

You can push together two twin mattresses if you choose, but you might struggle to find perfectly matching accessories for them because two twin mattresses together do not equal a standard mattress size.

Is a king mattress too big for one person?

While a single person can purchase a king mattress if they want to, it’s not necessary. Queen mattresses are more than enough for a single person. It’s unlikely a single person would be able to take up all the space on a king bed, but if you have a big enough bedroom and a comfortable budget, nobody’s stopping you from getting one.

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

Since split kings have a rather unique construction, they need special bedding to suit them. You should use twin XL fitted sheets for the individual mattresses, then one king flat sheet and comforter on top of both mattresses.

You can find split king sheet sets with all of this included, but they are a bit rare. So, you’ll most likely have to buy the individual sheets for your split king, which can get expensive.

How do you keep a split king bed together?

Most split king beds come with an iron plate connector to keep the beds together, but if you DIY’d your split king and bought two twin XL beds separately, there are other solutions you can try.

An easy way to keep a split king mattress together is by using a fitted bed frame. The railing will keep the two mattresses in place, minimizing the risk of them slipping out of place or coming apart.

You can also use a non-slip mattress pad or dual-sided tape between the mattresses and the foundation. The resistance from the padding or tape will stop the mattresses from shifting.

Do you need different sheets for an adjustable bed?

King and split kings are both commonly paired with adjustable bed bases. With an adjustable bed base, you should ideally get fitted sheets with extra deep pockets or sheet suspenders. This way, the fitted sheet is secured to your bed and won’t pop off in the middle of the night.


Although king and split king mattresses are the same bed size, split kings aren’t necessary unless you share a bed with somebody who has different firmness needs. Split king beds are also a great choice for couples who have different schedules and don’t want to disturb each other when getting in and out of bed.

King mattresses work well for couples with similar firmness preferences. Single adults can use a king bed if they choose, but this size of a bed isn’t always necessary for solo sleepers.

Harrison Wall is Sleep Junkie’s business strategist and sleep analyst. He also authors posts on bedding and mattress accessories. Harrison regularly coordinates with new mattress companies and tests their products to determine what really helps you get better rest and have brighter mornings.

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