A California king bed is approximately 72 inches wide and 84 inches long. These measurements can vary within half an inch, depending on brand and style.
In the United States, mattresses are most commonly made in twin, extra long twin, full, queen, king or California king. A California king bed is the longest and 12 inches wider than a queen. It is 4 inches narrower and 4 inches longer than a regular king bed.
The California king mattress was first manufactured in Los Angeles in the 1960s. It is also known as the Western king, and the regular king mattress is known as the Eastern king.