Time to get the tape measure out

What is the ideal print book size? I never used to think about it. At one point in the distant past I probably thought all paperback books were equal. But as an author I do have to think about it now, since so much of the work depends on having a fixed size in mind at the start - cover dimensions, interior templates, image sizes. In the past I used A5 as a print size (or "trim size") for my books. It worked out cheapest when there are lots of pages; the cover ratio work for e-books too, so the same cover image can be used for print, Kindle, Smashwords etc. without redesigning it; and it looked nice when held in my hand. For various reasons I won't go into I'm now going to switch from A5 to another size, and I can tell you - it is a bit of a pain. Once I make this change I want to know that I won't have to do it again for a long, long time.

Once I started looking into this I realised that it's more complicated than I'd expected. I was told "these are the sizes of books" - promptly contradicted by other sources quoting different standard sizes. It didn't help that sometimes dimensions are given in cm, sometimes mm, sometimes inches; sometimes the horizontal dimensions are given first (6" x 9"), sometimes the vertical (210 mm x 148 mm); sometimes names are used instead of dimensions (Demy, A Format, Trade); and dimensions for the "same" sizes vary according to different sources. So much for standardisation.

If you want to experience this yourself, do as I did in the image above: hunt for books all round your house. Sort them into piles by size. Measure the books and note the size, plus how many books of that size there were. I'd be interested in the results - feel free to enter them in the comments. You'll probably find the same as me, that there are a range of sizes, but when same-size books are piled up there should be one or two piles which are taller than the others (though probably still with a couple of mm variance between books in that pile).

One of my aims was to identify the main book sizes, and which were supported by the services I wanted to use. No point picking a size that can't be printed by the main print-on-demand specialists, or where templates wouldn't be available if I wanted to try them. So I created the table below using these sources of information for what sizes were supported:
Here's my summary table. In many cases I've put the source for the information/figures, especially where there's disagreement such as C Format sizes in mm.

NameSize (mm)Size (inches)Used for?BookDesign
Crown Quarto246 x 189
7.44 x 9.69
??NY[But says not standard]Y
????7 x 10
Royal234 x 156
234 x 153
6.14 x 9.21
??NYY [But says not standard]Y
US Trade229 x 152
6 x 9
Longer books; hardbacks [BDT]YYYY [Cream only]
C format;
216 x 140
216 x 138
216 x 135
5.5 x 8.5
Hardbacks [GA];
“trade” paperbacks [BDT]
A5210 x 148
5.83 x 8.27
"Most popular size for
European print-on-demand books" [BDT]
Y [2way only]YNY
??203 x 133
5.25 x 8
Novels; memoirs; space-saving novels [BDT]YYYN
??203 x 127
5 x 8
Compact paperbacks [BDT]Y [2way only]YY [But says not standard]N
B Format; 
“Large Crown”
198 x 129
198 x 130
5.06 x 7.81 [ISCS]Literary books [GA]NYYN
??178 x 127
5 x 7
A Format178 x 110
178 x 111
4.37 x 7
Supermarket /
airport bestsellers [GA]
Pocketbook175 x 108
B6148 x 105

Things to note:

  • The table is not not complete, since I missed out many other sizes. IngramSpark alone offers 22 trim sizes! I just tried to include key ones, otherwise the picture gets much more complicated. So I avoided square shapes, and very large ones (A4, US letter, graphic novel sizes etc).
  • Warning! It seems that when the dimensions are in mm they often (but not always) are listed with the long edge/height first; when the dimensions are in inches they are listed with the short edge/width first; sites that list both will switch the x and y dimensions round when they move from mm to inches, e.g. IngramSpark.
  • Warning! Sometimes the mm dimensions don’t match up on different sites even though they use the same name, or they don’t match a conversion from inches exactly. I’ve done a best guess. But when sites only use one criteria (mm, inches, or one of the names) it means it isn’t always clear what size they are talking about.

After examining the table, it seems like 6" x 9" or 5.5" x 8.5" are the most widely supported (the former in the US, the latter in the UK). I was getting somewhere.

My measurements
Going back to the measurements I did at the start (see image at the top), my results were as follows. I worked in mm, but often books differed from each other by 1 or 2 mm and I still put them in the same group, since this variation could be affected by printing processes.

137 x 212 mm = 1 book
127 x 204 mm = 1 book
130 x 199 mm = 10 books
122 x 184 mm = 1 book
109-112 x 177-179 mm = 10 books
106 x 173-175 mm = 2 books

So, there were 10 books at 130 x 199 mm - this is the B Format/“Large Crown” used for literary books. The 10 books at 109-112 x 177-179 mm (obviously a more nebulous specification) are probably the A Format, used for supermarket / airport bestsellers.

It's interesting that all my books fell short of even the 5.5" x 8.5" (216 x 135-140 mm), let alone the 6" x 9" format. So analysing my books threw a spanner in the mix, since if I adopted the A or B format I wouldn't be able to use a Book Design Template or print via Lulu (and CreateSpace for A). These smaller sizes would also be more expensive since there are fewer words per page, so more pages - which increases the cost for the reader. With a book like 2000 Tunes, which is 140,000 words, that could be significant.

I decided to ask friends and colleagues online about what formats they thought of as the best compromise, both as readers and as authors; which size were they more likely to pick up in a bookshop or library? I offered a range of trim sizes from my table above, but only four of the sizes were voted as popular:

  • 11 votes: [no name] (203 x 133mm / 8 x 5.25 inches) 
  • 9 votes: US Trade (229 x 152mm / 9 x 6 inches)
  • 5 votes: C Format / Demy (216 x 135/140mm / 8.5 x 5.5 inches)
  • 4 votes: B Format / Large Crown (198 x 130/129mm / 7.81 x 5.06 inches)

Some of that is from regional differences: in the US 6" x 9" is standard, but that is seen as too large in the UK market. It is interesting that no-one voted for the A Format, used for supermarket bestsellers (even though many of the books I found around my house were in that size). Some people didn't vote but mentioned preferences in the comments - in most cases these were variants of 8 - 8.5" x 5 - 5.5". I think one of the things that puts me off that size range is the number of variants that fall within it. It's just not as clear cut as some of the others.

In the feedback there were comments favouring the smaller sizes:

"They are much easier to hold and to carry around. Trade paperbacks and hardbacks are "indoor" reads only as they are far too big to put in my bag"

"Not that clear about the sizes myself. Basic/average paperback for me. Current book is 5" x 8" or 13cmx 20cm which is about average & feels perfect."

"I find hardbacks and trade paperback take up a bit too much room."

"I really don't mind. I guess an average sized paperback is best for carrying around, and if I know that I'm going to be going on a train journey I do tend to make sure that the book I take is smallish. I do love hardbacks and trade paperbacks though."

"As long as it's a book I don't mind."

"I prefer smaller for portability but size has yet to put me off a book I want to read"

"I measured mine too and considered all the options and went for 8x5 too on the basis that was the most common size on my shelves and an easy to handle. I recently produced the same book in a 5.5 x 8.5 hardback - I chose one of the smaller sizes for hardback so it was still easy to handle but larger than paperback to emphasize the difference. There was a noticeable difference in page count too - 376 in paperback, 316 in hardback which seemed quite a lot for the overall small size difference!"

"I chose the UK trade paperback size 8.5 x 5.5 inches simply because that was the size my trad published books were and I wanted a uniform size. I believe 6 x 9 inches is the default US size, and it would certainly mean less pages, but that size looks out of place on UK book store shelves. But it's probably the first choice if you're in the US."

"I use 5 x 8. I measured a bunch of paperbacks on my shelves, and most of them came out smaller than that."

"You are right to look at this. Booksellers often refuse to stock the larger sizes. They want 8 x 5 inches or nearest UK equivalent."

There were also some useful comments about the importance of the text size:

"Normal size paperback so it fits in my handbag properly. Any other sizes especially bigger I just find heavy and awkward to hold and read. Smaller is fine so long as the font size doesn't go very small."

"I don't carry books around - I read them at home, and use my kindle when out + about - so book size is kind of immaterial to me. I quite like the larger format - looks good on shelves, spine creases less. What is important though is print size and readability - these days I frequently decide not to buy a book because the print is too small or insufficiently black + white." 

"Kindle is my first choice. Books don't leave the house so any size is good for me to read. I can't stand small text because it makes reading more difficult. If I want to read for a long time I need the text to be a good size."

Size impact on cost
It's interesting that there was a preference for smaller trim sizes. However, they have more pages and can be more expensive (and possibly have smaller fonts). The opposite applies as you move up through the sizes. Si size has an impact on cost. What if the larger size format was £2 cheaper? Would we still prefer a smaller size and be happy to pay that extra? It's an interesting question.

"Cost would be a big factor in my choices. The only thing that I might pay a little more for would be if I were collecting a series and wanted the books to match on my shelves."

I was curious about cost differences so knocked up a 100,000 word nonsense book.
6 x 9 inches = 379 pages; A5 = 427 pages; 5.25 x 8 inches = 504 pages.
I had a look at the cost estimate tool on Lulu which says the 6x9 would cost £7.23; the A5 (smaller) would cost £7.85; they don't do 5.25 x 8 inches, but I'm guessing it would be around £8.50. So there's quite a markup on smaller sizes, which must get passed on to the reader (or cut the profit of the author). I did a similar test on this print cost tool at Completely Novel. The same book would cost £5.79 in a smaller format (Demy) with more pages but only £4.54 in the larger format with fewer pages. About a £1.30 difference. Cost certainly pushes things towards larger sizes.

Of course, sometimes publishers try to mitigate the cost of popular small sizes by reducing the font size to cram more words on to the page. But this can make reading difficult for many people (as seen in the comments above), so is not an ideal solution.

So small books = popular, but more expensive (more pages) and/or smaller fonts.
Big books = less popular, but cheaper (fewer pages) and easier to read in terms of font size.

Where does all this leave me? I think I've made my mind up. 5.5" x 8.5" is the size I think I'll move to. It is most widely supported by print-on-demand service providers (though not by Lulu); it has different dimensions but almost the same surface area as A5, so shouldn't change the page count much; and it's the more UK-based size out of the two I narrowed it down to (and I'm a UK writer - if I wrote in the US I'd probably go for 6" x 9", for similar reasons). It's taken a long time to make that decision but I think I'll be happy with that choice.