Formatting · Topic 1 of 5
Trim Size
What to do
Choose the physical page dimensions your printed book will be (for example 5" × 8" or 6" × 9"), before you set up anything else about your interior layout.
Why it matters
"Trim size" just means the finished, trimmed page size of your printed book, the width and height after the printer cuts the paper down. Every other formatting decision (margins, font size, how many pages your book runs) depends on this one choice. Pick it after you've formatted and you'll likely have to redo your layout from scratch. Confirm your chosen size is actually offered by your printing platform, Amazon KDP and IngramSpark both publish their supported trim size lists, before going further.
Steps for your program
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Common mistakes to avoid
- Choosing a trim size because it "looks nice" on screen without checking it's actually offered by your printer.
- Picking a size that doesn't match genre expectations, an oddly large novel or a tiny nonfiction reference book can look self-published in a way that hurts trust.
- Changing trim size after formatting is mostly done, this reflows every page and undoes margin, gutter, and page-count work.
Completion checklist
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What does this mean? What is trim size?
What is trim size?
Trim size is the width and height of a finished printed page, after cutting. It is not the cover size or the size of a sheet of printer paper.
Try this: For example, a 6 × 9 inch book is 6 inches wide and 9 inches tall. Measure two or three similar books, then choose a size that suits yours. You do not have to copy another book.
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What does this mean? What does supported mean?
What does supported mean?
Your printer must offer your chosen size for the particular format, paper, ink, and page count you plan to use. A paperback and hardcover may have different options.
Try this: Check the current specifications for the exact edition you are making. If using both KDP and IngramSpark, check both before committing to the layout.
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What does this mean? Page size versus paper size
Page size versus paper size
The document or exported print PDF needs dimensions that match the printer’s requirements. The default Letter or A4 page is usually not your finished book size.
Try this: For a book without bleed, a 6 × 9 inch trim generally means 6 × 9 inch interior pages. A bleed interior needs the extra area specified by the printer. See the Bleed lesson before exporting. Reflowable ebooks do not use a fixed printed trim size.
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Troubleshooting
What if my printing platform doesn't support the exact size I want?
Pick the closest supported size instead of a custom one. Printers only manufacture books at their listed sizes, a non-matching size will get rejected or auto-adjusted in a way you don't control.
Can I use a different trim size for print vs. ebook?
Yes, and in fact you should think of them separately. Ebooks reflow to fit any screen, so trim size only applies to your print edition. Choose the print trim size based on genre and printer support; the ebook doesn't need one.
Reference: KDP’s trim size, bleed, and margin requirements. Check your chosen printer’s current specifications for your edition.