Reading ePubs uses the standard Adobe page number calculation.
ADE describes in a high level the ADE calculation. Do note that the
Quote:
|
1024 unicode characters as the page size
|
refers to the size of the compressed content within the ePub file, and not the expansion of the content.
Some general discussion can be found in the Wiki at
Page_numbers.
Some books do contain an Adobe pagemap which does make the number displayed closer to what you would expect.