12mo

With dimensions of approximately 7.5" x 9.5" (190mm x 240mm), the 12mo format has a surface area around 71 square inches or 459 square cm. Also referred to as Duodecimo or Twelvemo, this book size gets its name from 12 leaves of paper folded into one signature during old bookbinding practices. Slightly larger than mass market paperbacks, 12mo became a common size for small hardcover novels and nonfiction books. The 7.5" x 9.5" dimensions allow for portability while having ample text per page for comfortable reading. Especially popular for hardcovers and small reference books in the United States, 12mo hits a versatile sweet spot between being compact yet large enough for legible formatting. Originating from early modern printing, the 12mo size can comfortably fit 250-350 pages printed on both sides. With its roots tracing back to the 1600s, 12mo remains a useful size today for portable editions, though trade paperbacks have now overtaken it in popularity. Its continued success stems from striking an optimal balance of hand-held portability while allowing plenty of content per page.