We all know that book sizes are important; if you have done any shelving at all, you know that a non-standard book size will throw off your entire shelf. It’s frustrating for shelvers everywhere – but books of different sizes can be fascinating for readers! Our eyes are drawn to things that are different from all the other materials around it, so a non-standard size book may be more likely to get checked out – a great outcome for libraries!

But did you know that there are names for all those different sizes?? I had no idea there were so many different classifications for book sizes! (Of course, we are in the classification profession; so it’s probably not a surprise that we can even break down book sizes so carefully!)

Check out this chart from the ALA by way of Wikipedia :

“The following table is adapted from the scale of the American Library Association,^[1][13] in which size refers to the dimensions of the cover (trimmed pages will be somewhat smaller, often by about ¼ inch or 5 mm^[2]). The words before octavo signify the traditional names for unfolded paper sheet sizes. Other dimensions may exist as well.^[12][14]

Book formats and corresponding sizes

Name	Abbreviations	Leaves	Pages	Approximate cover size (width × height)
				inches	cm
folio	2º or fo	2	4	12 × 19	30.5 × 48
quarto	4º or 4to	4	8	9½ × 12	24 × 30.5
Imperial octavo	8º or 8vo	8	16	8¼ × 11½	21 × 29
Super octavo	8º or 8vo	8	16	7 × 11	18 × 28
Royal octavo	8º or 8vo	8	16	6½ × 10	16.5 × 25
Medium octavo	8º or 8vo	8	16	6½ × 9¼	16.5 × 23.5
octavo	8º or 8vo	8	16	6 × 9	15 × 23
Crown octavo	8º or 8vo	8	16	5⅜ × 8	13.5 × 20
duodecimo or twelvemo	12º or 12mo	12	24	5 × 7⅜	12.5 × 19
sextodecimo or sixteenmo	16º or 16mo	16	32	4 × 6¾	10 × 17
octodecimo or eighteenmo	18º or 18mo	18	36	4 × 6½	10 × 16.5
trigesimo-secundo or thirty-twomo	32º or 32mo	32	64	3½ × 5½	9 × 14
quadragesimo-octavo or forty-eightmo	48º or 48mo	48	96	2½ × 4	6.5 × 10
sexagesimo-quarto or sixty-fourmo	64º or 64mo	64	128	2 × 3	5 × 7.5