Quick answer: King mattresses (76″x80″) provide unified sleeping surface for couples. Split King uses two Twin XL mattresses for personalized comfort. Ideal for different firmness needs or adjustable beds. Choose King for simplicity; Split King for customization and partner compatibility issues.
| Feature | King | Split King |
|---|---|---|
| Surface | Single unified mattress | Two Twin XL side-by-side |
| Customization | Same firmness both sides | Different firmness each side |
| Motion Isolation | Good | Excellent (complete separation) |
| Adjustable Base Compatible | Compatible only with king | Full compatibility with twin XL or king |
| Bedding | Standard king sheets | Two Twin XL sheet sets |
| Best For? | Similar sleep preferences | Different needs/adjustable bases |
| Moving the Mattress? | Can be difficult | Moderate (two smaller pieces) |
Key Takeaways
- Couple compatibility: King suits partners with similar preferences; Split King essential for different firmness needs or sleep disorders
- Customization benefits: Split King allows individual adjustable bases, firmness choices, and temperature control
- Practical considerations: King simpler for bedding; Split King easier to move but requires separate sheets
- Sleep quality impact: Split King eliminates compromise, reduces motion transfer, prevents partner sleep disruption
- Quick links: Compare king vs Cal king and split king vs twin XL. Read the full list of mattress sizes.
Both king and split king are the largest standard mattress sizes on the market. Their wider size allows for more personal space, so couples don’t feel crowded. But which mattress should you choose? We share information on both sizes, including benefits and drawbacks.
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What Is a King Size and Who Needs It?
A king size mattress, or eastern king mattress measures 76 inches by 80 inches. King size mattresses are a great choice for couples and offers more personal space for both sleepers.
Also known as Eastern king beds, these types of mattresses fit comfortably in a 12 feet by 12 feet bedroom, including a couple of nightstands with walking space.
Benefits
- Largest standard mattress size
- More personal space
- Best for large master bedrooms
Drawbacks
- Not ideal for bedrooms smaller than 12 feet by 12 feet
- Difficult to move due to large size
What Is a Split King Size and When Should You Choose It?
A split king mattress is the same size as a king-size bed, except it is two twin XL mattresses side by side instead of one uniform bed. Split kings are great mattresses for couples with differing sleep preferences, and they’re compatible with adjustable beds.
Split king mattresses allow sleepers to adjust the bed to their preference without disturbing the comfort of their sleep partner, unlike traditional king-size beds. If paired with a split king adjustable bed for couples, each partner can have their half in different configurations.
Plus, some companies offer customized split kings that allow couples to choose how firm or soft they want their bed to feel. A split king bed with two firmnesses is excellent for couples with very different sleep needs.
It’s smart to make sure each side of the split king bed has the same mattress thickness, though, for a more even look. Particularly when using a single bed frame for your split king.
Benefits
- Perfect for couples with differing sleep preferences
- Can prevent a sleep divorce
- Easier to move—two smaller mattresses instead of one large bed
- Isolates motion transfer
Drawbacks
- Separate fitted sheets
- Too big for some bedrooms
- May need to consider how to keep a split king together
How Does King vs Split King Affect Sleep Quality?
Partner Compromise Issues: Traditional King mattresses force couples to compromise on firmness, often leaving one partner with poor spinal alignment and pressure point pain. Split King eliminates this compromise entirely.
While King mattresses provide good motion isolation, Split King offers complete motion separation. This is essential for couples where one partner has restless sleep, gets up frequently, or has different sleep schedules.
Now, both sizes have their own adjustable base sizes that match their dimensions. But split kings on adjustable bases better addresses sleep disorders like sleep apnea, acid reflux, and snoring without affecting your partner’s sleep position.
Health Benefits of Proper King Size Choice
Relationship Harmony: Split king prevents the “mattress compromise” that leads to one partner’s poor sleep affecting relationship dynamics and daily mood.
Individual Health Needs: As couples age, different health conditions require different sleep solutions. Split King provides future-proofing for changing medical needs.
Sleep Disorder Management: Split king allows treatment of individual sleep disorders without affecting partner, crucial for conditions like sleep apnea or restless leg syndrome.
How to Choose Between King and Split King
Choose King If:
- Both partners prefer same firmness level
- You prioritize simple bedding and setup
- Neither partner has sleep disorders requiring elevation
- You sleep synchronously (same bedtime/wake time)
- Budget is primary concern
Choose Split King If:
- Partners need a dual firmness mattress (firmness mismatch causes pain)
- One partner has sleep apnea, acid reflux, or snoring issues
- Different sleep schedules or one partner is restless sleeper
- You want future flexibility for aging/health changes
- Either partner wants adjustable base features for couples
Red Flags for King:
- One partner complains mattress is too firm/soft
- Sleep disruption from partner movement
- Different temperature preferences
- One partner has medical conditions requiring elevation
Which Amerisleep Mattresses Work Best in King and Split King Sizes?
Quick Guide: A 30-Second Summary
| Best King Mattress Overall | Amerisleep AS3 |
Best King Size Mattress Overall
Amerisleep AS3
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Price Range: $999 to $2148
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Mattress Type: Memory Foam
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Mattress Firmness: 5 to 6 out of 10 (Medium)
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Mattress Thickness: 12 Inches
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Available In: Twin, Twin XL, Full, Queen, King, California King, Split King
The AS3’s medium firmness and advanced materials make it ideal for couples choosing traditional king who have similar comfort preferences.
Built with plant-based Bio-Pur® memory foam that’s more breathable and responsive than traditional petroleum-based foam, the AS3 provides balanced support that works for most sleep positions and body types while staying cooler throughout the night.
The HIVE® transition layer creates five zones of targeted support, ensuring proper spinal alignment whether you’re sleeping alone on a King or with a partner.
For split king setups, the AS3 offers exceptional flexibility. Partners can pair it with firmer AS2 for back/stomach sleepers or softer AS4/AS5 for side sleepers, creating personalized comfort zones that eliminate mattress compromise.
The Bio-Pur® foam’s motion isolation technology becomes especially valuable in king size, preventing sleep disruptions when one partner moves during the night, while the breathable materials help regulate temperature for couples who sleep hot.
Both king and split king configurations come with our 100-night sleep trial, allowing couples to test whether unified or split setup works better for their relationship harmony and individual comfort needs, plus our 20-year warranty protects your investment regardless of which configuration you choose.
Pricing of Amerisleep King Mattresses
| Mattress | Price |
|---|---|
| AS1 | $1199 |
| AS2 | $1399 |
| AS3 | $1599 |
| AS3 Hybrid | $1699 |
| AS4 | $1599 |
| AS5 | $2199 |
| AS5 Hybrid | $2399 |
| Amerisleep Organica | $1599 |
Other Mattress Sizes
If you feel that a king or split king mattress isn’t the right size for you, other standard sizes include twin, twin XL, full, queen, California king, and split California king.
Twin Size
Twin size mattresses measure 38 inches by 75 inches and are the smallest standard mattress size on the market. Twin beds are great for children and for adults looking to save on space. For families with more than one child, bunk bed frames are a perfect space-saving option for multiple twin size mattresses in a single room.
Twin XL Size
Twin XL mattresses are 38 inches by 80 inches. They’re most common in college dorm rooms and great for tall people looking for more sleep space. Like twin mattresses, twin XL beds comfortably fit in smaller living spaces.
Full Size
Full-size mattresses are 54 inches by 75 inches. Full bed sizes are wonderful for teenagers and adults looking for more room to spread out. Full-size mattresses are also good for restless sleepers or those who switch between different sleeping positions at night.
Queen Size
A queen-size bed measures 60 inches by 80 inches. Queen mattresses are one of the best options for single adults and couples who like to sleep close to each other. They’re also great as guest beds.
California King Size
California king mattresses have similar mattress dimensions as king-size, but while a king-size bed is wider, a Cal king mattress is longer and more narrow at 72 inches by 84 inches.
Also known as “western king,” California king beds are a good option for taller individuals or couples who like to sleep closer together. The extra four inches allows those over 6 feet tall stretch out their feet comfortably.
Split California King Size
Split California king beds measure 72 inches by 84 inches. Like the standard king-size, California king is also available in split sizing, though they’re not as widely available as split king. A split California king bed has two halves, each 36 inches wide.
A split California king mattress is another great option for couples with different sleeping preferences and is also compatible with adjustable beds.
Choosing the Right Mattress Firmness
As we’ve said, the key advantage of a split king is that it allows sleepers to enjoy their preferred mattress firmness. Now, the importance of mattress firmness lies in its direct impact on sleep quality and overall well-being.
A mattress that aligns with an individual’s preferred sleeping position ensures proper spinal alignment, reducing the risk of waking up with aches and pains.
Side Sleepers
The best mattress for side sleepers is typically medium to soft. This level of firmness helps relieve pressure points at the shoulders and hips, providing optimal support and comfort. A mattress for side sleeping with some give allows the spine to align properly, reducing the risk of discomfort and promoting a restful night’s sleep for side sleepers.
Back Sleepers
Back sleepers generally benefit from a mattress with a medium-firm firmness. This level of support in a mattress for back sleeping helps maintain the natural curvature of the spine, preventing backaches. A balance between comfort and firmness ensures that back sleepers receive adequate support while enjoying a plush surface for a comfortable night’s sleep.
Stomach Sleepers
Stomach sleepers typically find a medium-firm to firm mattress most suitable. This firmness level helps prevent the lower back from sinking too deeply into the mattress, maintaining spinal alignment. A supportive surface in a mattress for stomach sleepers is crucial to prevent discomfort and potential long-term issues.
Combination Sleepers
Combo sleepers, who switch between different sleeping positions, often benefit from a medium to medium-firm mattress. This firmness level accommodates various sleeping styles, providing enough support for back and stomach sleeping while offering sufficient comfort for side sleeping. A versatile mattress for combination sleepers caters to their changing preferences throughout the night.
FAQs
Is a split king bigger than a California king?
Yes, a split king is bigger than a California king because a standard king is bigger, if only by a small margin. A standard king offers 6080 square inches, while a California king offers 6048 square inches.
Is a split king good for couples?
Yes, each side of the split king can be adjusted independently, allowing partners to customize their own sleep experience. And it minimizes motion transfer that can disturb the other person.
How do you keep a split king from sliding apart?
Use a non-slip mattress pad or grip underneath each mattress and cover both with a tight fitted sheet. There are also special straps for split king mattresses, securing the two halves together.
Can you put 2 twin beds together to make a king?
Yes and no. You can’t put two standard twin beds together to create a king-size bed. But two twin XL mattresses form a split king.
What is the point of a split king?
Separate twin XL mattresses accommodate differences in mattress firmness, elevation, or other sleep preferences. And a split king minimizes motion transfer.
What is the disadvantage of split king?
There is presence of a gap or seam in the center, which may be felt by some individuals. And finding bedding that fits a split king properly can be challenging.
Will a split king hurt our relationship?
Split king maintains same sleeping space as regular king while allowing comfort customization. Most couples report improved relationship satisfaction from better sleep quality.
What if only one of us wants adjustable base features?
Split king is perfect for this. One side adjustable, one side standard platform, both getting their preferred sleep setup.
Is the gap in split king noticeable during sleep?
Setups with proper connectors and mattress toppers make the gap virtually undetectable during sleep.
Which is better for couples with different body weights?
Split king allows each partner to choose appropriate firmness for their weight, preventing heavier partner from sinking too much or lighter partner from inadequate pressure relief.
Do you fall in the crack of a split king?
No, the divide in a split king is about as thin as the space between your mattress and bed frame. You might feel it if you lie down on top of it and you should be careful with your fingers if you pair it with an adjustable bed. But otherwise, it shouldn’t be noticeable.
How Do You Choose Between King and Split King?
No matter which size you choose, the best mattress size will comfortably fit the bedroom with walking space and areas for furniture for aesthetic appeal. A king-size is a great option with its wider dimension, offering more personal space for couples.
A split king size is another great option, providing catered sleeping preferences so both couples have optimal comfort without compromise. Both a king and a split king mattress measure 76 inches by 80 inches and fit in a king bed frame. They are excellent choices for any master bedroom.
About the author
Sanchita Sen is a full-time writer focusing on the sleep health and mattress industry. She is a former journalist who has written numerous articles on the healthcare sector. Some of the topics she has covered include how to lucid dream, fever dreams, melatonin for sleep, and best gel memory foam mattress. Sanchita holds a Master of Arts in Communications from Convergence Institute of Mass Media and Information Technology Studies. She is also a published author, who seeks inspiration from both real life and the world of fiction.
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