16mo

With dimensions of approximately 6.5" x 9.5" (165mm x 240mm), the 16mo format has a compact surface area around 62 square inches or 400 square cm. Also referred to as Sixteenmo, this book size gets its name from 16 leaves of paper folded into one signature during old bookbinding practices. Larger than Duodecimo but smaller than trade paperback sizes, 16mo became popular for small portable editions of novels, poetry, and nonfiction. The 6.5" x 9.5" size allowed books to be lightweight and easy to carry, while having enough text per page for comfortable reading. Especially common in the 19th century for condensed classics and children's literature, 16mos were ideal for accessible entertainment on-the-go. Originating from early printing press formats, the versatile 16mo size could comfortably fit around 200-300 pages printed on both sides. While less ubiquitous today, 16mo remains useful for pocket-sized books when portability and condensing content down are key aims. Its success stems from striking a versatile balance of travel-friendly compactness and legible text formatting.