Bed sizes explained

I can never remember which California vacation rental has a California King bed and which one has a (Eastern) King bed. I've also had trouble figuring out why some sheets fit well, and others don't, most notably Ikea sheets on non Ikea mattresses.

You see, I did inventory today at my beach rental, AND I need a new mattresses for the king beds at the beach, and in the desert. So I measured the mattress, and then had to look up what the measurements meant. Turns out it's a California King at the beach condo.

Mattress size (width × length)
Single/twin 39in × 75in
Twin extra long 39 in × 80 in
Double/full 54in × 75in
Queen 60in × 80in
King 76in × 80in
California King 72in × 84in
(source: http://en.wikipedia.org/wiki/Bed_size)

A couple of things I learned:
-two twins do not make a king (wider & shorter)
-two twin xl do not make a king (wider, but same length)
-Ikea sheets are made for Ikea mattresses not US (the sizes are completely different)
-no wonder sheets don't always fit right

Maybe I'll figure out the depth of mattresses and sheets that fit them next?

I know this is an odd thing to fixate upon, but these things matter when you deal with people and their sleep needs on a regular basis!