Dimensions: 80” L x 76” W (two twin XL mattresses)
A split king mattress combines two twin XL mattresses to form a standard king size—offering both the width of a king and the flexibility of individualized comfort. It’s a popular option for adjustable bases, where each sleeper can customize their side without disturbing the other. Great for couples with different sleep preferences, schedules, or those who prefer personalized sleep setups (e.g. their own sheets & bedding).
Best for: couples who want personalized comfort and compatibility with adjustable bases.
Room size: A split king mattress fits best in a spacious bedroom that’s at least 12 x 12 feet.
Learn more about Casper mattress sizes in our Mattress Size Guide.