California King Foundations / Box Springs

Who Needs a Cal King Foundation?

You need a California King foundation if you own a Cal King mattress and your bed frame does not include built-in slat support. Cal King dimensions (72" x 84") are 4 inches narrower and 4 inches longer than a standard king (76" x 80"), so the two sizes are not interchangeable. Always verify your mattress size before ordering a foundation.

Mattress Compatibility

Any Cal King mattress works on a Cal King foundation. Rigid foundations with flat slats are the best choice for memory foam and hybrid models. If you are also shopping for a new mattress, our mattresses by type collection includes Cal King options across all construction types and comfort levels.

Profile Height Options

Cal King foundations are available in low (4" to 5.5"), standard (7" to 7.5"), and high (9" to 9.5") profiles. Because Cal King mattresses are often 12 inches thick or more, a low profile foundation helps keep the total bed height from becoming uncomfortably tall, especially if your bed frame already adds height.

Delivery and Split Options

Cal King foundations can be challenging to navigate through hallways and staircases due to their 84" length. A split Cal King foundation divides the base into two manageable halves that reassemble on the bed frame. If your home has narrow access points, the split option eliminates the need for window deliveries or disassembly.

Pairing with a Cal King Bed Frame

If you need a bed frame to house your foundation, our California King beds collection includes platform, panel, and upholstered frames designed for Cal King dimensions. Make sure the frame's interior clearance accommodates the foundation profile height you have selected.