How to Prepare a Print-Ready PDF: A Factory Preflight Checklist

2026-09-10 Β· Qicai Press Blog

A print-ready PDF is a single file your printer can impose, plate, and print without stopping to fix anything: final trim size with 3 mm bleed on every edge, images at 300 dpi in CMYK, all fonts embedded or outlined, and total ink coverage within the limits of the paper. This checklist explains each requirement, and the file mistakes that most often delay book printing jobs.

What "Print-Ready" Actually Means

Printers use the term "print-ready" (or "press-ready") for a file that needs no correction before plate-making. Every correction we have to make — adding bleed, converting colors, replacing a missing font — means a round trip between you and our prepress team, and each round trip can cost days. A clean file goes straight to proofing.

One important point for books: send us single pages in reading order, not printer's spreads. Imposition — arranging pages onto large press sheets — is our job, because it depends on our press sheet size, the binding method, and the folding equipment. If you supply reader spreads or imposed spreads, we have to break them apart first.

Page Setup: Trim Size, Bleed and Safe Margins

  • Trim size: set your document page size to the final trimmed size of the book (for example 6 x 9 in or A5), not to a larger sheet with crop marks drawn on it.
  • Bleed: extend any element that touches the page edge 3 mm (0.125 in) beyond the trim on all sides. Cutting tolerances in binding are fractions of a millimeter, and bleed is what absorbs them.
  • Safe margin: keep text and critical artwork at least 5 mm (about 0.2 in) inside the trim line — and further from the binding gutter on perfect-bound books (see below).
  • Covers: paperback covers and dust jackets are separate files built on a template that includes the spine. Confirm the spine width with us before finalizing the cover — it depends on your final page count and paper bulk.

Images: Resolution and Color Mode

Images should be 300 dpi at their placed size. That last part is what matters: a photo that is 300 dpi at full size but enlarged to 200% in your layout drops to an effective 150 dpi and will print soft. Line art (barcodes, logos, black-and-white diagrams) needs 600-1200 dpi to keep edges crisp.

Convert images from RGB to CMYK before or during export. Screens display a wider range of saturated colors than offset ink can reproduce, especially bright blues and greens. Converting early lets you see the real result and adjust, instead of being surprised on press.

Color: CMYK Builds, Ink Limits and Black Text

Two color problems cause the majority of file corrections:

  • Four-color black text. Body text should be 100% K only. Small text built from all four CMYK channels shows colored fringes wherever registration shifts by a fraction of a millimeter.
  • Excessive total ink coverage. The sum of C+M+Y+K in any area should stay under roughly 300% for coated paper, and around 240-260% for uncoated paper. Above these limits the ink cannot dry properly, which causes set-off and smearing between sheets. Large black backgrounds print richer with a supporting build such as 40C/30M/30Y/100K — but confirm the exact recipe with us, because it depends on the paper and press.

If your book uses brand-critical spot colors (Pantone), keep them as spot colors in the file and tell us — do not silently convert them to CMYK.

Fonts: Embedded or Outlined

Every font used in the file must be embedded in the PDF, or converted to outlines. If a font is missing, the prepress system substitutes it, and substitution changes line breaks, spacing, and sometimes the whole layout. In your export dialog, "embed all fonts" should be on, and no font should be flagged as restricted by its license. Avoid "faux" bold or italic applied inside the layout software — use the real bold or italic font file so it embeds and prints correctly.

Book-Specific Checks

  • Page count: offset books print in folded signatures, most commonly 16 pages each, so a page count that is a multiple of 16 (128, 144, 160...) uses paper most efficiently. Other counts are possible, but may add a partial signature and extra cost.
  • Crossovers: images spanning two pages lose a few millimeters in the gutter of a perfect-bound or hardcover book, and the two halves can misalign slightly. Keep faces and critical details out of the gutter.
  • Blank pages: include intentional blanks in the file itself so the pagination stays unambiguous.

Export Settings: PDF/X and Marks

For book printing, PDF/X-1a is the safest standard: it forces CMYK (plus declared spot colors), embeds all fonts, and flattens transparency. PDF/X-4 is the modern alternative that keeps live transparency for the RIP to process — both are acceptable, but tell us which one you used. Include the bleed in the exported PDF. Crop marks and registration marks are optional (our imposition software adds its own), and never password-protect the file.

The 10-Point Preflight Checklist

  1. Page size equals the final trim size; single pages in reading order
  2. 3 mm bleed on every edge where elements run off the page
  3. Text at least 5 mm from trim, further from the gutter
  4. All images 300 dpi effective at placed size (600+ dpi for line art)
  5. All colors CMYK, plus declared spot colors
  6. Body text 100% K only; total ink coverage under 300%
  7. All fonts embedded or outlined
  8. Page count planned around 16-page signatures
  9. Cover file built to the confirmed spine width
  10. Exported as PDF/X-1a or PDF/X-4 with bleed included

What Happens When Your File Reaches Our Factory

Every file we receive goes through a preflight inspection before plate-making: resolution, color mode, bleed, and font embedding are checked one by one, and anything that fails goes back to you with a specific description of the problem. We never fix a file silently, because a silent fix changes what you approved. If you are not sure whether your file is ready, send it with your inquiry and our prepress team will check it as part of the quotation.

Ready to print? Send us your files and specifications, and we will confirm the preflight results together with your quote.

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