Amazon, Prepublishing, Tips & Tricks

Trim Size

Physical books come in a variety of sizes. Some are tall. Some are short. Some fit in the back pocket, and others lounge in bags. But what size should your paperbacks be?

Typical Sizes

The typical books I format fall under these sizes:

  • 4 x 6” (154 x 102mm)
  • 4 x 7” (178 x 102mm)
  • 4.25 x 7” (178 x 108mm)
  • 5 x 8” (203 x 127mm) **
  • 5.25 x 8” (203 x 133mm) **
  • 5.5 x 8.25” (210 x 140mm)
  • 5.5 x 8.5” (216 x 140mm)
  • 6 x 9” (229 x 152mm) **

The three with the ** are the top requested.

These aren’t all the options available, and where you print copies may have trim sizes that other companies don’t offer.

Now that looks like a lot of choices, and it can be overwhelming at first, but here are a few things to consider:


For kids’ books—beginner books and beginner chapter books—looking on the local shelves might give you the answer, but for most writers, this isn’t where we compete, and as such, genre plays little in the role of trim size.

Spine Width

It takes 100 pages before a book has a thick enough spine to do any form of consistent spine writing.  I say consistent because

  • the writing will be small, maybe a 12 point font
  • spine shift—100 pages seems like a lot, but for POD, that 1/16″ or 1/8″ inch shift they sometimes have can cause your type to spill across the edge and onto the front or back cover. I’ve seen this on shelves at BAM, so it isn’t just an indie problem.

If you want a decorative spine with frills and elegant fonts, series logos, publisher logos, or similar things, you want to go with a trim size that gives you a decent page count.

Here’s a handy calculator to figure out your spine width if you know your page count and your trim size—

Page Count

Word count plays a considerable role in trim size.

If you tried to fit 100,000 words into a 5 x 8” you will find while the page count is good, the thickness can be costly in printing price and in reader’s ability to hold.

This website ( gives you the ability to estimate the page count based on word count and approximate trim size. Whatever count you get there, you’ll want to add 10 pages for front and back matter, and take the number of chapters and divide it by 3. If this isn’t your first book, and you know you’re going to go a sneak peek of the next book, add a few more page. Maybe you decide you don’t need a dedication, so drop 2 pages. Maybe you want to add author’s notes and a CTA, add a few pages.

Using the math from that page, here’s an example:

  • 70,000 total words / 300 words per page = 233 pages
  • 17 chapters / 3 = 5.6 ,round up = 6 pages
  • Front and back matter = 10 pages
  • 233 + 6 + 10 = 246 pages total for a 5 by 8”

Is this 100% accurate? No. So many factors go into how many words fit a page (font size, line spacing, font, margins) that you can’t get an accurate answer but that website gives you a ballpark answer.

My estimate of page count to word count ratio is lower than theirs, but as stated above, there are many factors that go into words per page ratio:

  • 5 x 8” (203 x 127mm) = 200 words per page
  • 5.25 x 8” (203 x 133mm) = 250-300 words per page
  • 6 x 9″ (229 x 152mm) = 300-400 words per page

The ballpark figure isn’t to give you an exact answer; it’s to determine if you have enough spine width.

Reader Perception

Readers on Amazon won’t care if your book is a 6 x 9” or a 4 x 6″ when they order it. Readers at festivals and book signings, however, shop with their eyes.

Does your book feel comfortable in their hands? Does it feel flimsy? Does it feel massive? Does it feel/look like a good choice for the price?

A thin 6 x 9” will visually look like a poor investment. A decent size 5 x 8” might sell for $12.99 at a festival, though the book store’s $9.99 might make it a hesitating thought and might cut into the bottom line.

Perception is the key. Does it look like a worthy investment? Even to the people who order on Amazon, the perception they gain while holding the book can make it a book they love to share or a book that, despite loving the story, left them slightly unsatisfied.


PODs charge a flat rate per book + a price per page to get the cost of a printed book.

When potential clients don’t know what trim to go with, I offer these suggestions:

  • Under 40,000 words = 5 x 8” or smaller
  • 40,000-80,000 words = 5 x 8” to 5.25 x 8’
  • 70,000-120,000 words = 5.25 x 8” to 6 x 9”
  • 110,000 and up = 6 x 9”

Yes, there are some overlaps.

Readers prefer series to be the same size. If your books are near the threshold of going up a trim size, and your drafts are longer than your previous ones, make that jump up a size to accommodate for the potential thicker books in the middle or end of a series.

If you’re not sure which trim size to go with, order a proof. IngramSpark will allow you to change the trim and paper (cream or white) at any time. If you use KDP, once the trim and paper type are locked, they can’t be changed.

A thin 6 x 9” is cheaper than a fat 5 x 8” in author pricing, but does the cost of one or the other negate using it? That’s an individual choice, and it is a mix of how much you can charge for it, give the reader a pleasurable experience, and still profit from it.

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This post has been edited by ProWritingAid.


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