What many people refer to as a regular or standard king is called an Eastern King by the mattress industry and measures at 76” wide by 80” long. It is the size found in most furniture & mattress stores on display and in stock. The California king also referred to as the western king is 72” wide and 84” long. This is a special size that is normally not stocked by stores. In the past and still today the Cal. King is more commonly used for hard side waterbeds.
Do they make a special mattress to fit inside a waterbed?
Frequently people ask for foam or spring mattresses to drop into a hard side waterbed. The industry name for such a bed is a waterbed insert. This is a mattress undersized 2” in both length and width so you can get your hands between the mattress and frame to make the bed. The finished mattress measures only 70” X 82” a tad smaller than the traditional California King mattress and a great solution for people that own waterbeds.
A common problem when buying a California king mattress and box spring is that there are very few headboards available in the California king size width. When buying a headboard or a headboard and footboard nearly all are only available in Eastern King and then have a second attachment on them for Cal. Kings because of the small 4 inch difference leaving two inches of extra headboard on each side of the Cal. King mattress making it a one King size fits all bed. This is a method that has been used on combination Queen / Full headboards for years. If you place the mattress set on a metal frame make sure it can be adjusted to fit a California king 72 inch mattress width.
In those situations where people decide to transition from their wood frame waterbed but keep their California king insert they will then need to find a box spring to put underneath it. Be aware that if you go out and buy a California king box spring it will be 72” X 84” and your insert may only be 70” X 82”. You may need to order a custom size boxspring to fit your waterbed insert mattress.
Will my old sheets work on my new bed?
California king and eastern king sheets will not interchange. You may get by with flat sheets, but the fitted sheet definitely will not work. I should point out there are differences between California king sheets for a spring mattress and those made for a waterbed. California kings conventional sheets usually have a flat top sheet and the bottom sheet is fitted like a shower cap making it hard to get on a hard side waterbed. Waterbed sheets on the other hand usually have 4 corner pockets and some top sheets are sewn to the foot of the bottom sheet. We have found separated sheets to be more popular with the top sheet having pockets only on the foot end only and the bottom having a standard pocket in each of the four corners. We call this a 6-pocket sheet set.