Square, tall and pocket-sized: leaving the standard trims
Most books should be one of the conventional sizes, for the reasons set out in Choosing a trim size. Some books should not. A square format is the natural shape for photography. A short, wide page suits a gift book. Poetry often wants a tall, narrow page that lets a long line sit on one line. A children's picture book at 6 x 9 looks like a novel with pictures in it.
If your book is one of those, the unusual trim is not an indulgence. It is the correct answer. What follows is what it costs, so you choose it with the bill in front of you.
Fewer printers carry it
This is the first and largest cost. Each printer publishes its own list of trim sizes, and the lists do not match. A size that is routine at one is unavailable at another, and a size available in paperback at a given printer may not exist there in hardcover.
That matters more than it sounds. A book in a size only one printer offers is a book tied to that printer. If their price rises, their quality slips, or you later want a second source, you have no move that does not involve redrawing the cover.
The four sizes named in Choosing a trim size work across all four printers here — Amazon KDP, IngramSpark, Lulu and B&N Press — in every binding. Stepping outside that set means checking each printer individually, and accepting that the answer will differ between them.
Distribution gets narrower
Retail and library distribution runs on catalogs of standard sizes. Some channels will not take a title outside their accepted range at all, and others take it but treat it as a specialty item. Terms and eligibility change often enough that the only sound advice is to check the current rules for the specific channel you care about before you commit.
Physical shelving is the same argument in wood. Bookshop and library shelves are built for conventional heights. An oversized book gets laid flat, shelved in a different section, or declined. A very small one disappears between its neighbors.
Shipping and handling change with it
Shipping is priced in bands, by size and weight, not smoothly. A book that crosses a band — too large for a standard mailer, too thick for a letter rate in some countries — costs more to send on every copy, forever. If you sell direct, that lands on you rather than on a store, and it is worth pricing before you design.
Your comps stop looking like you
The comparison test is the one most authors skip and then regret. Put your book beside five recent titles aimed at the same reader. If all five are the same rectangle and yours is a square, a browsing reader reads that difference before reading your title.
For a photo book, that difference says specialist and is doing exactly what you want. For a thriller it says self-published. The format is a signal either way, so decide which signal you are sending. Comp titles: reading the shelf you want to be on covers how to assemble that comparison set honestly.
In the Cover Maker. The trims here are the four that every one of our printers actually prints — 5 × 8, 5.25 × 8, 5.5 × 8.5 and 6 × 9 — and the tool knows which bindings each printer offers at each of them, so it will not let you design a hardcover at a size that printer does not make. A deliberately unusual format is work for a designer building to one printer's own template. Start a book → · about the Cover Maker
Check availability before you design, not after
This is the practical rule, and it is the one that saves the most work: confirm the trim is available at the printer you will actually use, in the binding you actually want, before a single design decision is made.
The reason is that artwork proportions are not portable. A cover designed for a square book cannot be re-cut to 6 x 9. It has to be redrawn: the image is the wrong shape, the type block was composed for a different rectangle, and cropping to fit destroys the composition that made the square worth choosing. An interior is no kinder — change the trim and the text re-flows from page one, the page count moves, and the spine moves with it.
Do it in this order.
- Confirm the size and binding at your printer, today. Lists change. Take it from their current specification, not from a blog post or from what was true last year.
- Check a second printer while you are there. Even if you have no plans to move, knowing whether you could is worth the five minutes.
- Confirm your distribution channels accept it if bookstores, libraries or a specific retailer are part of the plan.
- Then design, and not before.
The spine math does not change
One thing an unusual trim does not affect: how thick the book is. Bulk comes from paper, and paper bulks per sheet regardless of how wide or tall the sheet is.
KDP's white stock runs 0.002252 inches per page and cream 0.0025 inches per page whatever the trim. Lulu divides the page count by 444 and adds 0.06 inches for glue. IngramSpark is not a formula at all but a curve taken from their own templates, and B&N Press publishes a measured table. Those are the same numbers for a 5 x 8 and for a square book of the same page count on the same paper. See How to calculate spine width for the working.
What does change is the page count feeding that math. A wider page holds more words, so a format change moves the page count, which moves the spine, which changes the wrap. The math is stable. Its input is not.
The short version
An unusual trim is a legitimate choice for a book whose content genuinely needs it, and a costly affectation for a book that does not. The cost is optionality: fewer printers, narrower distribution, higher shipping, and a design you cannot take with you. Pay it deliberately, or pick a standard rectangle and put the effort into the cover.
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: Metric trim sizes, and books printed outside the US · More: Choosing a trim size · Why a printed cover never lands exactly where you put it · Where to print: KDP, IngramSpark, Lulu and B&N Press