How to Prepare a Comic PDF for Printing

What the printer's preflight checks

Before a human looks at your art, software checks the PDF's geometry, and most rejections happen there. In order of how often they bite:

1. Page size. Every page equal to trim plus bleed. For a US comic that is 6.875 x 10.5 in (495 x 756 pt).
2. TrimBox. A box inside the page telling the printer where the cut is. Without it, bleed is meaningless.
3. Page count. A multiple of four for interiors.
4. Consistency. No rotated pages, no odd sizes, no spreads mixed with singles.
5. Fonts embedded. Or converted to outlines.
6. Image resolution. 300 DPI at placed size.
7. Colour. CMYK for offset; RGB accepted by most digital and POD printers. Ask.
8. Flattened transparency. Live blend modes are a common source of "it printed differently".

The PDF preflight tool checks the first six in your browser before you upload anything.

Setting up the export

From an image editor (Photoshop, Clip Studio, Procreate)

Export each page as a flattened PNG or TIFF at bleed size and 300 DPI, then assemble in a layout tool or a PDF combiner that sets page boxes. Image editors that "save as PDF" generally write one MediaBox and no TrimBox, which passes some printers and fails others; if that is your only route, tell the printer the trim size in writing.

From a layout tool (Affinity Publisher, InDesign, Scribus)

Set the document to trim size (6.625 x 10.25 in) with bleed 0.125 in in the document settings, not by making the page bigger. In the PDF export choose PDF/X-1a or PDF/X-4, include bleed, leave crop marks off (marks push the page out of size), and the exporter writes MediaBox, BleedBox and TrimBox correctly.

Single pages, not spreads

Export as single pages unless the printer explicitly accepts spreads. Art that crosses the gutter is fine; the pages just need to be delivered separately. The preflight tool flags a PDF whose pages are two trims wide.

Page boxes, briefly

A PDF page has up to five boxes. Two matter here. The MediaBox is the whole page, which for print should be trim plus bleed. The TrimBox is the finished size, inset by the bleed. A BleedBox is optional and usually equals the MediaBox. When the tool reports "bleed but no TrimBox", the file is the right size but the printer cannot tell where to cut.

Naming and packaging

• One PDF for the interior, one for the cover, unless the printer's uploader wants them together.
• If delivering individual page files, zero-pad: page_01, page_02. Otherwise page_10 sorts before page_2.
• Keep the PDF under the upload limit; 300 DPI JPEG at quality 90 to 95 is fine for colour, PNG or lossless for line art.

Then order one

A single proof is the cheapest mistake you will ever make. Check the spine text, the safe area on the busiest page, and the darkest panel for muddy blacks. The print-ready checklist lists the rest.

Questions