I'm sure we're all aware of the size of a piece of A4, or A5.
I can picture them, and recognise them when I see them, but couldn't quote exact dimensions without checking!

But sheet music comes in many sizes, and a couple of old pieces I've recently picked up seem to evade description. So my thought was that this called for a thread to establish what,if anything, is the correct description of various sizes of sheet music, song books, etc.,

So to start the ball rolling, is there a standard description for the following paper sizes?
20¼" wide by 14" high. (This is measured at the open centre page, i.e. a double page)
19" width * 12¼" height (also to the open double page)

And if anyone does know the correct terminology, what else can we add to the list?

My personal preference would be to keep the discussion in Imperial, but for the benefit of all, the two sizes noted above are:
515mm * 355mm
480mm * 310mm


Nigel