With dimensions of approximately 7" x 10" (178mm x 254mm), the Medium Octavo format has a surface area around 70 square inches or 451 square cm. Falling between standard Octavos and Royal Octavos in size, Medium Octavos became popular in the 18th and 19th centuries for compact editions of literature, nonfiction, and reference books. The 7" x 10" size allowed for portability while having ample text per page for comfortable reading. Especially common in the United Kingdom for bibles and dictionaries, Medium Octavos hit a versatile sweet spot balancing compactness and smooth formatting. Originating from old bookbinding practices, the name Octavo refers to eight leaves folded into one book signature. The Medium Octavo size could comfortably fit around 250-300 pages printed on both sides. While less common today, Medium Octavo remains useful for portable books that fall in between mass market paperback and trade paperback dimensions. Its success stems from formatting readable text efficiently in a hand-held package - not too small yet not too bulky.