How to Prepare Your Book File for Print: A Practical Guide for Self-Publishing Authors

May 21, 2026

If you've finished writing your book and you're about to send your files to a printer, this is the part of self-publishing where everything can quietly go wrong. The manuscript is done. The cover is designed. The printer says they need a "print-ready PDF." And suddenly you're staring at terms like "bleed," "CMYK," "embedded fonts," and "spine width" — none of which you signed up to learn when you started writing.

This guide will fix that. By the end, you'll know exactly what your interior PDF and cover PDF need to look like, the most common mistakes that ruin print runs, and how to check your own files before you upload them anywhere.

A quick note about us: we run RexPress, a book printing service for self-publishing authors. Part of what we do is review files for print-readiness — we've seen what works, what fails, and what authors most commonly get wrong. This guide is the same advice we'd give a friend who didn't want to pay us.

Why File Prep Matters More Than Authors Realize

Most self-publishing authors spend months on the writing, weeks on the editing, and an afternoon on the file prep. That's backwards.

Here's the math. A print run of 250 hardcover books costs roughly $5,000-$10,000. A print run of 1,000 paperbacks costs $3,000-$6,000. If your files have problems that don't get caught until after the books are printed, you don't get a refund. You get a stack of unsellable books in your garage and you start over.

The most expensive mistakes we see aren't from authors who are careless. They're from authors who assumed their files were ready because they exported to PDF and the file looked fine on screen. Print is a physical medium with mechanical tolerances. What looks perfect on your laptop can come back from the printer with cropped text, blurry images, white borders along every edge, or a cover that's drifted toward the spine.

The good news: every common file error is preventable. You don't need to be a print production expert. You just need to know what to look for.

If you'd rather skip the learning curve, we offer a free file review for any author who wants a second set of eyes on their PDFs before they commit to a print run. Submit your files here — we'll tell you in plain English what's print-ready and what isn't. Otherwise, keep reading.

The Two Files You Actually Need

Before we get into specs, it's worth clarifying something many first-time authors don't realize: every printed book requires two separate PDFs, not one.

The interior PDF is everything inside the book — title page, copyright page, table of contents, all the chapters, any footnotes or appendices, and the back matter. It's submitted as a single PDF with all pages in order, sized to your final trim size (the dimensions of the finished book).

The cover PDF is a single flat image containing your back cover, spine, and front cover laid out side-by-side as one wraparound spread. It's sized to the full wrap dimensions — meaning width = back cover + spine + front cover, plus bleed on all four outside edges.

These two files go through different production processes at the printer, and they have different specifications. Confusing the two — or trying to submit a single PDF with both — is one of the most common reasons files get rejected.

A few related points worth knowing up front:

You don't include a separate file for the dust jacket (if you're doing a hardcover with one). The dust jacket is just a different kind of cover file, treated the same way — a flat wraparound spread with bleed.

You don't submit ebook files when you're printing. EPUB and MOBI files are for digital distribution only. Print needs PDFs.

You don't need to provide separate image files for any photos or graphics inside your book. As long as your images are embedded properly in your interior PDF at the right resolution (more on that in a moment), the printer doesn't need anything else.

If you're working with two well-prepared PDFs — one interior, one cover — you have everything a printer needs. Everything else in this guide is about getting those two files right.

Interior File Requirements

Your interior PDF needs to meet eight specific requirements. Each one is simple in isolation, and miss any one of them and your file is at risk of being rejected, reprinted incorrectly, or printed in a way that disappoints you when the books arrive.

1. Correct trim size

The trim size is the final size of your printed book after it's cut. Common trim sizes for self-published books include:

5" x 8" — Mass-market paperbacks, mystery, romance, thriller
5.5" x 8.5" — General fiction, literary fiction
6" x 9" — Non-fiction, business books, memoir
7" x 10" — Workbooks, larger non-fiction, technical books
8.5" x 11" — Photo books, art books, children's books, cookbooks

Your interior PDF must be sized to your chosen trim size exactly. If you choose 6"x9" and your PDF is letter-sized (8.5"x11"), your printer will either reject the file or print it incorrectly. This sounds obvious, but it's one of the most common errors we see — authors who designed their book in Microsoft Word with default letter-sized pages and exported to PDF without changing the page dimensions.

2. Embedded fonts

Every font used in your interior must be embedded in the PDF. If you used a custom font for chapter titles, decorative drop caps, or any other styling, that font needs to be packaged inside the PDF itself.

If fonts aren't embedded, the printer's RIP (raster image processor) will substitute them with something else — usually a generic default — and your beautiful chapter headings will come out looking nothing like what you designed. Worse, you might not even know it happened until the printed books arrive.

Most modern PDF exporters embed fonts automatically, but it's worth verifying. In Adobe Acrobat, go to File → Properties → Fonts to see what's embedded.

3. Image resolution at 300 DPI minimum

Every image, photo, illustration, or graphic in your interior must be at least 300 DPI (dots per inch) at the actual printed size. Lower-resolution images will print blurry or pixelated.

This is where authors get caught: a 1500x1500 pixel image might look sharp on screen, but if you stretch it to fill an 8.5"x11" page, you've reduced its effective resolution to about 180 DPI — and it'll print fuzzy. The relevant question isn't "how many pixels does my image have" but "how many pixels per printed inch will it have at its final printed size."

Photos pulled from the web are almost always 72 DPI, which is fine for screens but unprintable. If you used web images anywhere in your book, replace them.

4. Correct color space

If your interior is color, every image and graphic must be in CMYK color space, not RGB. CMYK is what printers use; RGB is what screens use. Submitting RGB files will result in noticeable color shifts when printed — usually duller, darker, or flatter than what you saw on your monitor.

If your interior is black and white, all images should be converted to grayscale. Submitting color images for a B&W interior either wastes money (you'll pay color rates) or produces unpredictable conversion results when the printer's system tries to grayscale them automatically.

5. Proper margins

Margins are the space between the edge of the page and your content. For most printers, the minimums are:

Top, bottom, outside (non-binding) margins: 0.5" minimum
Inside margin (gutter): 0.5" minimum for books under 150 pages, increasing with page count

The inside margin (also called the "gutter") needs to be larger than the outside margins because pages curve inward toward the spine when the book is bound — and content too close to the gutter gets swallowed by the binding. Thicker books need wider gutters. A 600-page book typically needs a 0.875" gutter; a 100-page book can get away with 0.375"-0.5".

If your text or page numbers fall outside these margins, they may be cropped during the trimming process. The general rule: keep all content at least 0.5" from any trim edge.

6. Bleed (only if needed)

Bleed is extra space added to the outside edges of your pages so that images or backgrounds can extend all the way to the edge of the printed book. If anything in your interior — a photo, a colored background, a decorative element — is supposed to touch the edge of the page, you need bleed.

The standard bleed is 0.125" (1/8 inch) on three sides (top, bottom, outside) of each interior page. Bleed is NOT added to the inside (gutter) edge.

If your interior is text-only and nothing touches the page edges, you don't need bleed. Most novels and non-fiction books fall into this category. But if even one page has a full-bleed image, the entire file needs to be set up with bleed.

When you set up bleed, your PDF page dimensions will be slightly larger than your trim size. For a 6"x9" book with bleed, the page size will be 6.125" x 9.25" (added bleed on top, bottom, and outside, no bleed on the inside).

7. Single-page layout, not spreads

Your PDF must be exported with each page as a separate page — not as facing-page spreads. If you designed your book in InDesign or another layout program that displays facing pages side-by-side, make sure you export single pages, not spreads.

Printers process each page individually and impose them onto print sheets according to their own production logic. Spreads confuse this process.

8. Even total page count

The final page count of your interior must be an even number. Books are printed on large sheets that get folded and trimmed, and you can't have an odd number of pages — the last one would have nothing on the back of it.

If your final manuscript ends on an odd page, add a blank page at the end. Most printers will do this automatically if you don't, but it's better to control it yourself so the blank page lands where you want it.

Cover File Requirements

Cover files are where most authors get into trouble. Here's why: the interior is just pages — get the trim size and margins right and you're mostly fine. But a cover involves math (spine width calculations), a wraparound spread (back + spine + front as one image), and several variables that have to line up exactly with the interior file.

When something is off about a cover file, it's almost never one big mistake. It's usually one small spec being slightly wrong — and that one small thing causes everything else to shift.

Here's what a print-ready cover PDF actually needs.

1. Wraparound spread, not a single page

Your cover file must be one flat PDF containing the back cover, spine, and front cover as a single image, laid out side-by-side. Reading left to right: back cover on the left, spine in the middle, front cover on the right.

This is the single most common cover mistake we see. Authors upload just the front cover as a single page, expecting the printer to handle the rest. Printers won't. They expect one file containing the entire wraparound exterior of the book, sized to the full wrap dimensions.

If you have your front cover and back cover as separate files, they need to be combined into one wraparound spread before submission. Most cover design software has a "wraparound cover" or "full cover" template — use that.

2. Correct spine width

The spine width depends on three things: your final page count, your paper weight, and your paper type (offset vs. uncoated vs. coated). You can't guess this number — it has to be calculated.

For a 6"x9" paperback with standard 60lb paper:

100 pages = ~0.25" spine
200 pages = ~0.50" spine
300 pages = ~0.75" spine
400 pages = ~1.00" spine

For hardcover books, the spine includes the thickness of the cover boards and the wrap material, so the math is different — typically wider than paperback at the same page count.

The reliable way to get the right spine width is to use your printer's cover template generator. Every major printer (KDP, IngramSpark, Lulu) has a free tool: you enter your trim size, page count, and paper type, and it generates a PDF template with the exact spine width and overall dimensions for your book.

Do not design your cover without using a template. Designing a cover with a guessed spine width is the #1 reason covers come back shifted or misaligned. If your interior page count changes (because you added a chapter, or your editor cut content), your spine width changes too — which means your cover file needs to be rebuilt on a new template.

3. Full wraparound dimensions with bleed

Your cover PDF's overall dimensions must equal:

Width = back cover width + spine width + front cover width + 0.25" total bleed (0.125" on each outside edge)

Height = trim height + 0.25" total bleed (0.125" on top, 0.125" on bottom)

For a 6"x9" paperback with a 0.5" spine:

Width = 6" + 0.5" + 6" + 0.25" = 12.75"
Height = 9" + 0.25" = 9.25"

So your cover PDF would be 12.75" x 9.25".

If your cover file dimensions don't match these calculations exactly, the printer's system will try to fit your design into the correct dimensions — which usually results in the front cover artwork drifting toward the spine, white edges appearing where bleed should be, or text getting cut off near the trim line.

4. Bleed on all four outside edges

Unlike the interior (where bleed is only on three sides), the cover needs 0.125" bleed on all four outside edges of the wraparound — top, bottom, left (back cover edge), and right (front cover edge).

Any background color, image, or design element that's supposed to extend to the edge of the cover must extend into the bleed area. If your design ends exactly at the trim line, you'll get white slivers along the edges of your printed book because of normal trimming variance.

5. CMYK color space

Covers must be designed and exported in CMYK color space, not RGB. This is even more critical for covers than for interior images because the cover is the first thing readers see — and color shifts are most noticeable on solid backgrounds and brand colors.

Designers using web-oriented tools (Canva, Photoshop set to RGB by default) often miss this. The vibrant blues and bright reds that look perfect on screen can come back from the printer noticeably duller. If you designed your cover in RGB, convert to CMYK before you make final color adjustments — because the colors will shift during the conversion, and you'll want to fix them before submitting.

6. 300 DPI minimum

Same as interior images, but more critical: your cover image must be at least 300 DPI at the final printed size. A low-resolution cover is immediately visible to anyone holding the book — and it's the single thing that screams "self-published" loudest.

If your cover designer sent you a 1000-pixel-wide JPEG, that's not enough for a 6" wide print at 300 DPI. You need a file with at least 1800 pixels of width for the front cover alone (6" × 300 DPI), and proportionally more for the full wraparound.

7. All fonts embedded or outlined

If your cover uses custom fonts — for the title, author name, taglines — those fonts need to be either embedded in the PDF or converted to outlines (turned from text into vector shapes).

Outlining is the safer option for covers, because it removes any chance of font substitution during printing. The trade-off is that once you outline fonts, you can't edit the text anymore — so save an editable version separately before outlining for export.

8. Spine text considerations

If you're putting text on the spine (your book title, your name), there are practical limits worth knowing:

Spines under 0.25" generally shouldn't have text — it'll look cramped or get hidden in the binding
Text on the spine should be centered with at least 0.0625" (1/16 inch) clearance from the spine edges, since spine alignment can vary slightly during binding
Text should run top-to-bottom (read by tilting your head to the right) — this is the publishing industry standard

If your spine is too thin for text, leave it blank. Cramped spine text looks worse than no spine text at all.

Feeling Overwhelmed Yet?

If you've made it this far and you're starting to wonder whether your existing files really pass all these checks, you're not alone. Most authors get some of this right and miss one or two things — and the things they miss are usually invisible until the printed books arrive.

Submit your interior and cover files for a free review and we'll go through them against this exact checklist. You'll get a plain-English report telling you what's print-ready and what needs work, with no obligation to use us for the print run. We do this for free because it's the part of the process where authors most need a second set of eyes.

If you'd rather work through it yourself, the next sections cover the most common mistakes and a self-check you can run on your files.

The 5 Most Common Mistakes That Ruin Print Runs

After reviewing hundreds of author files, the same five problems show up over and over. If your file passes these five checks, you're in good shape. If any of them are unclear, that's where to look first.

Mistake #1: Cover designed without using the printer's template

This is the single most common cover problem. Authors (or their cover designers) build a cover based on a guessed spine width or generic dimensions, then upload it to a printer whose actual spine width for that book is different. The printer's system either rejects the file or — worse — accepts it and prints something with the front cover drifted toward the spine, the back cover misaligned, or the title text falling on the spine instead of the front.

The fix is always the same: download the printer's cover template (it's free), open it in your design software, and rebuild the cover on top of that template. Yes, this means starting over if your existing cover wasn't built this way. It's faster than reprinting 250 misaligned books.

Mistake #2: Low-resolution images that look fine on screen

Authors often pull images from their phone's photo library, Google Images, or stock photo sites without checking actual resolution. The image looks crisp on a laptop screen because screens display at 72-110 PPI — but when stretched to fill a printed page, the image effectively drops to 100-150 DPI and prints blurry.

The fix: every image in your file should be at least 300 DPI at the size it'll appear in the printed book. If you're using stock photos, buy the largest available version. If you're using your own photography, shoot at maximum resolution and don't downscale. If an image is too small to print at 300 DPI at your intended size, use it smaller or replace it.

Mistake #3: Color files designed in RGB instead of CMYK

Designers working in tools like Canva, Photoshop (with default settings), or web-based design platforms often work in RGB without realizing it. The PDF exports look perfect on screen, but when printed, colors shift — usually duller, muddier, or noticeably different from what was designed.

The fix: set your design software to CMYK at the start of the project, not at export. Converting RGB to CMYK at the end always causes some color shift; you want to design in CMYK so what you see is what you'll get.

Mistake #4: Missing or unembedded fonts

A cover designer sends you the PDF, you check that everything looks right on your screen, you submit it. But the designer's beautiful custom font isn't embedded in the PDF — only referenced. When the printer's system opens the file, it can't find that font, so it substitutes a default. Your elegant chapter heading becomes Times New Roman.

The fix for interiors: verify font embedding in Adobe Acrobat (File → Properties → Fonts). Every font should show "(Embedded)" or "(Embedded Subset)" next to its name.

The fix for covers: outline all text before exporting. This converts editable text into vector shapes, removing any chance of font substitution. Keep an editable version of your file for future revisions.

Mistake #5: Wrong file dimensions

The interior was designed at letter size (8.5" x 11") but the book is supposed to be 6" x 9". The cover was designed at 12" x 9" but the calculated wraparound dimension is 12.75" x 9.25". The dimensions are close enough that the file uploads without an obvious error, but the printer's system has to compensate — and what comes back isn't what you expected.

The fix: confirm your interior PDF is exactly your trim size (or trim size plus bleed if you have bleed), and confirm your cover PDF matches the wraparound dimensions from your printer's template. "Close enough" is never close enough in print.

How to Check If Your File Is Print-Ready

Before you submit your files anywhere, run through this self-check. It takes about 15 minutes per file and catches most of the common problems.

For your interior PDF

Open the PDF in Adobe Acrobat or Preview. Check that all pages display correctly with no missing text, broken layouts, or display errors.
Verify page dimensions. Right-click any page → Page Properties (or File → Properties → Description). The page size should match your trim size exactly (or trim size + 0.125" bleed if you have bleed).
Verify font embedding. In Adobe Acrobat: File → Properties → Fonts tab. Every font listed should say "Embedded" or "Embedded Subset." If anything says "Not Embedded," fix it before submitting.
Spot-check image resolution. Open the PDF in Photoshop (or any tool that lets you inspect images) and check that any photos or graphics display sharply when zoomed to 200%. If they look pixelated at 200% zoom, they'll print pixelated.
Verify color mode. For color interiors: confirm all images are CMYK, not RGB. For B&W interiors: confirm all images are grayscale, not color.
Check page count parity. Total pages must be even. Count them.
Check margins on a sample of pages. Pick five random pages from your interior. Verify that text, page numbers, and headers don't fall within 0.5" of any trim edge.

For your cover PDF

Confirm wraparound dimensions. Width should equal back cover + spine + front cover + 0.25" (bleed). Height should equal trim height + 0.25" (bleed).
Verify bleed. Background colors and edge-to-edge images should extend 0.125" past the trim line on all four outside edges. If your cover ends exactly at the trim line, you don't have bleed and you'll get white slivers when printed.
Verify color mode. The entire cover should be in CMYK color space.
Verify font handling. All text should either be embedded (Properties → Fonts) or outlined (no text recognized as editable text in the PDF).
Check spine alignment. Your spine text and elements should fall within the calculated spine width, with at least 0.0625" clearance from each spine edge.
Inspect resolution. Cover artwork should be 300 DPI at full printed size. Zoom to 200% — if anything looks pixelated, it'll print pixelated.

If anything fails

A failed check usually means one of three things: a small fix you can do yourself (changing color mode, embedding a font), a moderate fix that requires going back to your designer (rebuilding the cover on a proper template), or a significant rework (replacing low-resolution images you don't have higher-resolution versions of).

If you're not sure how to interpret what you're seeing, that's the moment to get a second opinion.

When to Get Help

You can do all of this yourself. Many authors do. But there are situations where the time, the stress, or the stakes make outside help worth it.

If your files came from a designer and you can't verify what they did. Cover designers vary in skill level. Some build files perfectly for print. Others build beautiful designs in RGB at low resolution, or skip the printer template, or hand you a JPEG instead of a PDF. If your designer's deliverables don't match what we've described in this guide and you can't get them to fix it, you need a print production specialist to either repair the files or rebuild them.

If your interior was created in Word or Google Docs. Both programs are excellent for writing but limited for print preparation — they can't reliably handle CMYK, bleed, embedded fonts, or precise trim sizing. If your manuscript exists in Word and you want a professional printed result, someone has to convert it to a proper layout (in InDesign, Affinity Publisher, or similar) before it's ready.

If you've already had a failed print run and you don't know why. This is the moment to stop guessing. Submitting the same problematic file to a different printer usually produces the same problematic result. A file review can tell you exactly what went wrong on the last attempt and what to fix before the next one.

If you have a launch date and no time to learn. Authors with book launches, speaking events, or seasonal deadlines often can't afford a learning curve. If you have 30 days until you need printed books, the math usually favors hiring someone who already knows how to do this rather than figuring it out under pressure.

For any of these situations, our free file review exists for exactly this purpose. We'll look at your files, tell you in plain English what's print-ready and what isn't, and give you a clear path forward — whether that path includes us or not.

Your Next Steps

What you do next depends on where you are with your files. Here's how to put everything you've just read into action.

If You're Just Starting File Prep

Don't rush this step. The temptation after finishing a manuscript is to power through file prep to "get the book out" — but spending an extra week or two getting the files right is always cheaper than reprinting a stack of books that came out wrong.

Pick your trim size first, then download your printer's cover template (KDP, IngramSpark, and Lulu all offer free generators). Build your interior in proper layout software — InDesign and Affinity Publisher are the professional options; Vellum is excellent for fiction and simpler non-fiction. Avoid building a final print file in Microsoft Word if you can; it works for drafting but lacks the precision for professional print output.

If You Think Your Files Are Ready

Run through the DIY checklist above before you submit anywhere. Most files that "feel ready" still have at least one issue — usually unembedded fonts, an RGB image that should be CMYK, or a cover built without using the proper template. Catching these now saves a print run.

If your files pass every item on the checklist, you're ready to upload. If anything is unclear or any check fails, get a second opinion before you commit.

If Your Files Aren't Print-Ready

This is exactly what our free file review is for. Send us your interior PDF, your cover PDF, and a quick note about your project — we'll review everything against the standards in this guide and tell you in plain English what's print-ready and what isn't.

Submit your files for a free review at RexPress. No quote required, no obligation, no upsell. If your files are fine, we'll tell you. If they need work, we'll tell you exactly what needs to change.

If You'd Rather Have Someone Handle the Whole Thing

For authors who'd rather not learn print specifications, manage designer revisions, or troubleshoot file issues, we offer a done-for-you service that covers file prep, proofing, printer coordination, and the entire print run.

Request a quote at RexPress and we'll respond within one business day with detailed pricing for your specific project. We work with authors at every stage — from manuscripts that need significant prep to print-ready files that just need a printer.

If You've Already Had a Failed Print Run

You're not alone, and the situation is fixable. Most failed print runs trace back to one or two specific file issues — once those are identified and corrected, the next print run works. The hardest part of recovering from a failed run is figuring out what actually went wrong, since printers usually won't tell you in detail.

Send us the files and the printed sample — we'll diagnose what went wrong and tell you what to fix before you try again.

The Bottom Line

Print-ready file prep isn't complicated, but it has to be precise. Two PDFs, sized correctly, in the right color space, with embedded fonts and adequate resolution — that's all you need. The authors who get this right end up with professional books they're proud of. The authors who skip it end up with expensive lessons.

Whether you tackle this yourself or get help, the goal is the same: files that print exactly the way you designed them, without surprises, every single time.

Back to blog