There are many variations in how octavos were produced. For example, bibliographers call a book printed as an octavo (eight leaves per full sheet), but bound in gatherings of 4 leaves each, an "octavo in 4s." <ref>[[Ronald B. McKerrow]], ''An Introduction to Bibliography for Literary Students'', Oxford 1927 and later eds., p. 28.</ref>
The actual size of an octavo book depends on the size of the full sheet of paper on which it was printed. The size of such sheets varied in different localities and times. A sixteenth century octavo printed in France or Italy is about the size of a modern cheap paperback, whereas an eighteenth
The [[Gutenberg Bible]] was printed as a folio in about 1455, in which four pages of text were printed on each sheet of paper, which were then folded once. Several such folded conjugate pairs of leaves were inserted inside another to produce the sections or gatherings, which were then sewn together to form the final book.