Although king beds only come in two sizes, these two sizes each have multiple names, which can lead to some confusion. The first is the standard king, also known as the eastern king, or sometimes just the king. If a mattress or bedding set is labeled as "king" and does not specify what kind of king, it is probably the standard king. The second kind of king bed, commonly known as the California king, is also known as the western king or abbreviated as the Cal king.
The main difference between standard king and California king beds is the size of the mattress. The standard king mattress measures 76 inches wide by 80 inches long. Its length is the same as a queen bed, but it is a full 16 inches wider to allow more space for two people to sleep. The California king mattress measures 72 inches wide by 84 inches long, which is 4 inches narrower and 4 inches longer than the standard king. It is the longest-size bed commonly available.
The California king-size of mattress is especially useful for people who are over 78 inches tall. The extra length allows tall people to stretch out more comfortably, and the loss in width is not very noticeable, especially because the California king is still a full foot wider than a queen mattress. Couples who are not especially tall typically choose to purchase a standard king so they can take advantage of the extra width.
Standard king mattresses are the size typically sold by mattress companies and in department stores. It is rare to find a mattress seller that carries California king mattresses without standard king mattresses. The opposite, however, is not true, as California king mattresses can be more difficult to find. As the name suggests, California king beds tend to be more readily available on the west coast. Sheets can also be difficult to find, as the fitted sheet needs to be specific to the type of king mattress, but most major chains carry both standard king and California king sheets.
Both sizes of king mattress can be difficult to fit into small bedrooms, because of the floor space they cover and because of the process of bringing the mattress through the house and into the bedroom. Standard king and California king mattresses both come with split foundations to ease the process of moving the bed.