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Belonging to the ISO A series, the 12mo paper size, also known as duodecimo or twelvemo, holds a unique position in the world of print and publishing. This format is traditionally used for pocket-sized books and small volumes, making it an ideal choice for publishers aiming to produce compact and portable literature.

The dimensions of a 12mo sheet are not standardized across different regions. However, it typically measures approximately 5 by 7.5 inches (127 by 190.5 mm), offering a balance between readability and portability. The size is derived from a full 'folio' sheet being folded into twelve leaves or twenty-four pages - hence the name 'duodecimo'.

12mo paper dimensions


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2A046.81 x 66.221189 x 1682119 x 1683370 x 4768
A120.51 x 0.7113 x 181 x 237 x 51
4A066.22 x 93.621682 x 2378168 x 2384768 x 6741
A110.71 x 1.0218 x 262 x 351 x 74
A101.02 x 1.4626 x 373 x 474 x 105
A3+12.95 x 19.02329 x 48333 x 48933 x 1369
A1+23.98 x 35.98609 x 91461 x 911726 x 2591
A0+35.98 x 50.87914 x 129291 x 1292591 x 3662
A64.13 x 5.83105 x 14811 x 15298 x 420
A55.83 x 8.27148 x 21015 x 21420 x 595
A48.27 x 11.69210 x 29721 x 30595 x 842
A311.69 x 16.54297 x 42030 x 42842 x 1191
A91.46 x 2.0537 x 524 x 5105 x 147
A216.54 x 23.39420 x 59442 x 591191 x 1684
A82.05 x 2.9152 x 745 x 7147 x 210
A123.39 x 33.11594 x 84159 x 841684 x 2384
A72.91 x 4.1374 x 1057 x 11210 x 298
A033.11 x 46.81841 x 118984 x 1192384 x 3370

Despite its smaller stature compared to other formats in the ISO A series such as A4 or A3, the 12mo paper size has played an instrumental role in shaping literary history. It was widely used during the Renaissance period for printing religious texts due to its convenient size that allowed easy transportation.

In today's digital age where e-books are gaining popularity, there's still a significant demand for physical books printed on 12mo paper due to their tactile appeal and collectability factor. They continue to be favored by readers who appreciate their compactness and ease of handling.

While not part of any ANSI series, this format remains relevant in modern times due to its versatility across various applications - from pocket diaries and notebooks to travel guides and novellas.

Other Formats in the Books Series

Interesting facts about 12mo

1: The Origin of 12mo Paper

12mo paper, also known as duodecimo or twelvemo, originated in the early 16th century. It gets its name from the fact that each sheet of paper is folded into twelve leaves or pages.

2: Compact and Portable

One of the main advantages of 12mo paper is its compact size. It was popularized for its portability, making it convenient for travelers and readers on the go.

3: Commonly Used for Pocket-Sized Books

The small size of 12mo paper made it ideal for pocket-sized books. Many literary classics were printed in this format, allowing people to carry their favorite stories with them wherever they went.

4: Variations in Folding Techniques

While the standard folding technique for 12mo paper involves folding a sheet into twelve leaves, there have been variations over time. Some printers used different folding methods to achieve a similar compact size.

5: Popular During the Renaissance

The use of 12mo paper became particularly popular during the Renaissance period. It allowed scholars and intellectuals to easily access and share knowledge through smaller books.

6: Precursor to Modern Paperback Books

The popularity of pocket-sized books printed on 12mo paper can be seen as a precursor to modern paperback books. The desire for portable reading material has remained constant throughout history.

7: Different Sizes within the Format

The term "duodecimo" refers more to a folding method than an exact size measurement. As a result, there can be slight variations in the dimensions of 12mo paper, depending on the specific folding technique used.

8: Commonly Used for Novels and Poetry

12mo paper was often used for printing novels, poetry collections, and other literary works. Its small size made it suitable for these types of texts, which were meant to be read leisurely.

9: Still Used in Fine Bookbinding

Today, 12mo paper is still utilized in fine bookbinding. It adds a touch of elegance to special editions or limited print runs of books, appealing to collectors and book enthusiasts.

10: A Testament to Historical Printing Techniques

The continued use of 12mo paper in certain contexts serves as a testament to the enduring legacy of historical printing techniques. It connects us with the past and reminds us of the evolution of book production over time.