Split King Mattress Size Guide
A Split King uses two Twin XL mattresses side by side in a King frame — ideal for adjustable base users and couples with different firmness or temperature preferences.
About the Split King Size
A Split King isn't a single mattress size — it's two Twin XL mattresses (each 38×80 inches) placed side by side to fill a King bed frame (76×80 inches). This configuration is the standard choice for adjustable base systems (each Twin XL has its own adjustable base, so each partner can independently raise the head or foot), and for couples who have dramatically different firmness preferences or temperature needs (using smart beds like Eight Sleep that allow per-side temperature control). The practical implications are significant: you'll need King-size sheets that can accommodate the 2-inch gap between mattresses (or specific Split King sheet sets), a King bed frame that accommodates two Twin XL bases, and either a mattress bridge/gap filler or the acceptance of a visible line between the two mattresses. The benefits — complete independence in sleep surface, firmness, and adjustable positioning — are compelling enough for the right buyer.
Best For
- ✓Adjustable base users (independent head/foot control per side)
- ✓Couples with very different firmness preferences
- ✓Smart bed users (Eight Sleep per-side temperature)
- ✓Those with significantly different schedules (minimize disturbance)
Not Ideal For
- ✗Couples who want a seamless sleep surface
- ✗Budget buyers (two mattresses + adjustable base is expensive)
- ✗Those without the need for independent adjustment
Top Mattresses Available in Split King
Lucid's mid-size budget memory foam with bamboo charcoal and gel infusion — widely available at major retailers and a strong value pick in the under-$350 queen segment.
The quintessential starter mattress — Linenspa's entry-level bonnell coil hybrid with a thin memory foam layer, widely available at major retailers for under $250 queen.
Allswell's 10-inch Hybrid uses gel memory foam over pocket coils with a firm support profile and Walmart fulfillment.
Allswell's entry hybrid pairs gel memory foam with pocket coils in a 10-inch, firm-feel build sold at Walmart.
Zoma's entry-level foam — Triangulex zone foam designed to accelerate muscle recovery during sleep. Budget price point with sports-recovery positioning.
The Allswell Luxe Medium is a 12-inch medium-firm hybrid with memory foam, pocketed coils, and a cool-to-touch fabric.
Split King Size — Frequently Asked Questions
What exactly is a Split King?
A Split King is two separate Twin XL mattresses (38×80 inches each) placed side by side in a King-size bed frame. Together they fill the same space as a King (76×80 inches). Each mattress is independent, allowing different firmness, adjustable base positions, and smart bed settings per side.
Do I need special sheets for a Split King?
Yes. Standard King sheets fit the overall dimensions but may bunch in the gap between mattresses. Purpose-made Split King sheet sets have a connected waistband that holds both mattresses together or include a mattress connector. Popular brands making Split King sheets include Sleep Number and Cariloha.
Is a Split King more expensive than a King?
Yes, significantly. You need to purchase two separate Twin XL mattresses (typically 80–100% of a King price each, so roughly double the mattress cost) plus two adjustable bases. The investment is only justified if you specifically need the independent adjustment capability.
Can you feel the gap in a Split King?
The gap between two Twin XL mattresses is a common concern. With high-quality bedding that straps the mattresses together and a mattress bridge/connector, the gap is barely noticeable. Budget options may leave a more obvious seam.
What adjustable bases work with Split King?
Most major adjustable base brands (Saatva, Leesa, Purple, Tempur-Pedic's ERGO, Sleep Number) offer Split King configurations. Ensure the base is rated for the combined weight of two mattresses. Some brands sell Split King bases as a matched pair.