My own wants in a quilt is for it to cover the bed and fall to the floor. I also want it to fold back, then cover the pillows. This usually winds up far larger than most quilts that are labeled KING. Then there is the question, does the pattern stop at the top of the mattress or does it fall over the top. Does it also include the cover for the pillows?
This would involve a lot of different calculations that would give me a headache.
As for the mattresses themselves, there seems to be a wide range of numbers there. There are...Crib. Bunk. Twin. Full. Extra long Full. Queen. Extra long Queen. King. California King. Eastern King.
And the way they're going, there is probably a Movie Star King, suitable for 3 to 9 people. Last time my DH and I bought one, we were overwhelmed at all the different sizes. Going online now, I found this.
-------------------
King Mattress= California King=Queen Mattress=Twin Mattress
Full Mattress=Custom Mattress=then there are the additions in length and width of each one. I'd suggest you go to a mattress store just for a visit. .........
And that was just one site.
My sister had to have a custom mattress made for her large antique bedroom set that she got at an antique store. I'll have to ask if she has to have the sheets made for her, never thought to ask before.