So you got a new king bed and now the FUN part, picking out just the right king size bed linens. Whoa! Be careful, not all king beds are the same. You would be advised to carefully measure the mattress length from head to foot, from side to side and especially the depth or thickness from top to bottom.
Most king mattresses measure 76 inches head to foot and 80 inches side to side. It's the top to bottom or depth that may cause a problem. Older king mattresses were pretty standard at 8 to 12 inches. Because of newer materials and manufacturers' competition, that has all changed. There are regular mattresses, air beds,water beds, foam top mattresses, and sofa beds. Some of these beds even move. These come in a variety of depths from the original 8 inches up to and including 21 inches.
For the most part, the thickness of the mattress is only relevant for the fitted bottom sheet. Instead of just elastic at the corners, some fitted sheets have elastic all around for a better fit and ease to put on and take off. The top sheets are pretty standard, usually 102 inches by 108 inches. Most other linens such as comforters, duvet covers, bedspreads and blankets are standard too. Wait a minute, my mattress measures 72 inches side to side and 84 inches from head to foot. WHY? You have a California King sized mattress. That needs a different size fitted sheet. Watch the depth size there as well. The other regular king size items will fit the California king mattress. There a few California king top or flat sheets that add a couple extra inches to the length.
There is another sneaky trick the Simmons mattress company came out with in the 1990s, the Olympic Queen. This mattress is 66 inches wide and so could fool you into thinking it is a King. It did not catch on, so not a lot of them are left out there. It is still possible to find bedding sized just for them. You might have to hunt the internet for them though.
And then there is the split mattress king bed. These are the Craftmatic or TempurPedic type beds, where each side moves independently. The head moves up and the lower part of the bed bends so the legs and feet are elevated. You need to decide if you need fitted sheets for each bed separately or one king sheet to cover both mattresses. If one person will be using the movement properties and the other won't, it might be wise to get separate fitted twin size sheets. Again measure to see if you need regular twin or twin XL sheets. From there you decide if you want to make each bed with its own top sheet, blanket, etc. or just use king bed linens to cover both. One more thing to consider, are you planning to add a solid foam or egg crate type topper on the mattress? Be sure to take that into consideration, when determining the thickness for the fitted sheet.
Using these steps to determine just the right king bed linens for your new bed, should ensure a comfortable nights sleep.