Split King vs King Mattress: What's the Difference?

King and split king mattresses are the same size, at 80 inches long and 76 inches wide, but a split king is made by pushing two twin XL beds together.

---

King mattresses have long ruled couples’ bedrooms. They’re big enough to comfortably fit two people, even restless sleepers, along with a child and a pet or two. But there’s another mattress option you might not know about, one that may suit sleep partners even more: a split king. 

In terms of size, there’s no difference between a king vs split king mattress. Both stretch 80 inches long and 76 inches wide.¹ But unlike a king mattress, a split king is actually two twin XL mattresses pushed together, designed to solve the time-old argument between uncompromising sleep partners: firm or soft? 

Explore the draws and drawbacks of standard king beds and decide if the split is worth it for you and your partner.

What is a King Mattress?

Let’s start with the straightforward one: a traditional king mattress. (And yes, there is only one mattress that makes up a king mattress). 

Definition and Dimensions

King mattresses are named as fittingly as a fitted sheet. They’re typically the largest standard mattress size available, standing (or lying) at a regal 80 inches long and 76 inches wide.¹

The occasional, ambitious single sleeper may choose a king mattress, but they’re usually best suited for couples who enjoy sleeping in the same bed, but like their space, too.  

Pros of a King Mattress

The main appeal of a king mattress is its impressive size. A larger mattress can benefit:

• Restless sleepers – Nighttime restlessness can be disruptive for both sleep partners. With a king, you can fit comfortably on your side of the bed, with enough space to toss and turn — and avoid accidentally kneeing your partner. 

• People with children or pets – If you let little ones or furry friends in bed with you, a king mattress can ensure that all sleepers have enough room to snooze soundly. Learn why sleeping with your dog can be beneficial in our research-backed blog.

Cons of a King Mattress

With mattresses, bigger is better — for some. These important factors may demote a king size mattress:

• If you have a smaller bedroom, a king bed may take up too much floor space.
• King mattresses can be cumbersome to move. 
• You and your partner must agree on the type of mattress you want.

The last point is often where sleepers run into the biggest issues. For couple sleepers, partners may not share the same tastes in mattresses. (They do say opposites attract, after all.)

If only you could split a king down the middle and tailor each side to each person’s unique preferences…

Wait a minute. 

What is a Split King Mattress?

And we’ve arrived at the epiphany mattress designers came upon long ago when they decided to start smashing two twin XL beds together to create the split king size mattress. Let’s talk about how it compares to the OG king. 

Definition and Dimensions

A split king mattress is technically two mattresses pushed together and placed on the same bed frame. Each half is a twin XL mattress, measuring 80 inches long and 38 inches wide.¹

When the two twin XL beds are flush, they add up to the same length and width as a standard king mattress: 80 inches by 76 inches. 

Pros of a Split King Mattress

A split king mattress allows both you and your partner to rule the bed equally. Here’s what sleepers love about them: 

• Complete customization – By far, the greatest advantage of a split king is that you and your partner can sleep on a mattress you love. With Casper, not only can you select your ideal mattress firmness levels, but you can opt for other mattress perks like Snow Technology and Zoned Support on one side or the other. 

“This is particularly useful for couples that have very different body proportions! For example, with a split king, a couple could have a super firm side for a tall or larger man, while the other side is plush to help contour to accommodate a petite woman’s waist and hips.”

– Jonathan Eilenberg, Certified Professional Ergonomist & Sr. Ergonomics Engineer

• Movability – A split king is uniquely mobile in contrast to a king. Instead of lifting and maneuvering an entire king mattress, you can move two smaller twin XL mattresses — which will definitely fit through your bedroom door. This is especially advantageous if you and your partner move frequently, or you enjoy routinely changing your bedroom layout. Learn more about how to move a mattress in our blog.

• Reduced motion transfer – One of the standout benefits of a split king mattress is the significant reduction in motion transfer. Since each side of the bed is a separate mattress, movements from one partner are less likely to disturb the other, leading to a more restful night’s sleep.

A split king can further enhance your sleeping experience if you put it on an adjustable bed frame. 

The Casper Adjustable Base Max allows both you and your bedfellow to lie in virtually unlimited positions at the touch of a button. Fully unwind before bedtime with 4-Zone Massage, and create your ideal sleep conditions with the Zero Gravity and Anti-Snore presets.

Cons of a Split King Mattress

What might cause the biggest split in opinion between you and your partner over this mattress option? The split itself. 

While the two twin XL mattresses lie snug against each other on the bed frame, there will still be a noticeable split where they meet. You or your partner may dislike this for a few reasons:

• You may feel uncomfortable if you turn over onto the split during the night
• It may make cuddling in the center of the bed less comfortable

What Sheets Do You Use for a Split King?

As the split king bed itself is fully customizable, so are split king sheets. Here are your main options: 

• Standard king sheets – Since split kings and standard kings share the same dimensions, you can use the same sheets for both. Covering both mattress halves with a single king-sized sheet may also help hide and minimize the center split. 

• Two sets of twin XL sheets – Do you and your partner also have differing sheets preferences? Whether you like to sleep on cotton, silk, or flannel, you can each make the bed with the sheets that make you feel the coziest. Learn more about flannel vs cotton sheets in our blog.

Do Split California King Mattresses Exist?

Yes, split California king mattresses do exist, though they are less common than standard split king mattresses. A split California king mattress has the same overall dimensions as a regular California king mattress – 72 inches wide by 84 inches long. However, it is divided down the middle into two separate mattresses, each measuring 36 inches wide by 84 inches long.

Choosing Between a Split King vs King

If you and your partner are split on the split king vs king decision, talk it out together. Consider both of your:

• Firmness preferences
• Sleeping habits
• Cuddling inclinations

If your needs align, go with a king. But if you simply can’t compromise, bridge the divide with a split king. 

Explore Split King and King Mattresses from Casper Today

Once you and your partner have settled the split king mattress vs king debate, find your ideal sleep solution with Casper. 

Each of our mattresses comes in both standard king and split king sizes, giving you and your partner the freedom to choose the mattress that matches you best. Whether you prefer classic comfort, enhanced support, or maximum coolness, we have the mattress you’ve been dreaming of. 

Browse online, or explore your options in person at a Casper Sleep Shop near you. 

Sources: 

1. National Council on Aging. Guide to Mattress Sizes and Dimensions. https://www.ncoa.org/adviser/sleep/mattress-sizes/