48mo

With very small dimensions of approximately 2.5" x 4" (63mm x 101mm), the 48mo format has a miniscule surface area around 10 square inches or 64 square cm. Also referred to as Forty-Eightmo, this book size gets its name from 48 leaves of paper folded into a single signature during old bookbinding practices. Smaller than 32mo sizes, 48mos were used for tiny novelty books and miniature travel editions. The extremely compact 2.5" x 4" size allowed books to be discreetly pocketed and easily concealed. Especially popular in the 19th century for minuscule versions of classics and tiny prayer books, 48mos showcased the limit for legible book typography. Originating from early printing press formats, 48mo could only comfortably fit around 50-75 teeny pages printed on both sides. More a display of craftsmanship than practical reading, 48mo remains essentially a curiosity demonstrating the extreme limits of book shrinkage. Its success was pushing how small books could become while still containing a readable amount of content.