on the size of the full sheet of paper on which it was printed. A demy quarto (abbreviated demy 4to) is a chiefly British term referring to a book size of about 11.25 by 8.75 in, a medium quarto 9 by 11.5 in, a royal quarto 10 by 12.5 in, and a small quarto equalled a square octavo, all untrimmed.

The earliest surviving books printed by movable type by Gutenberg are quartos, which were printed before the Gutenberg Bible. The earliest known one is a fragment of a medieval poem called the ''Sibyllenbuch'',