What are the five PDF page boxes?

MediaBox (the physical page size), CropBox (what's displayed on screen), BleedBox (TrimBox plus bleed margin), TrimBox (the final trimmed size), and ArtBox (the bounding box of the meaningful artwork). TrimBox and BleedBox are the two that matter most for print production.

Why are my TrimBox and BleedBox the same size?

Because your PDF export didn't include bleed. In Illustrator and InDesign, bleed has to be set in the Export dialog under Marks and Bleeds. If you skipped that step, the BleedBox defaults to equal the TrimBox and the file reports no bleed. Even if the artwork visually extends past the edge.

Which box does the press RIP actually use?

Commercial presses typically use BleedBox as the imposition boundary and TrimBox as the cut line. Sheet-fed offset and flexo both rely on these boxes being set correctly. If only MediaBox exists, the RIP has to guess, which usually means someone calls you asking for a new file.

TrimBox vs BleedBox: What's the Difference?

TL;DR

TrimBox is the final trimmed size. BleedBox is TrimBox plus bleed (typically 0.0625" or 0.125" larger on each side). If TrimBox equals BleedBox, your PDF has no declared bleed, and almost every automated preflight will flag it, even if the artwork visually extends past the edge. The fix lives in your export dialog, not the artwork itself.

The five PDF page boxes

The PDF spec defines five possible boxes per page. Not all of them have to be present, but the order matters: each box is contained within the next.

Box	What it is
MediaBox	The physical size of the page. The outermost box. Always present.
CropBox	What gets shown on screen in a PDF viewer. Usually equals MediaBox.
BleedBox	The area that includes bleed. Everything in this box gets imposed.
TrimBox	The final trimmed size, where the cut actually happens.
ArtBox	The bounding box of the meaningful artwork itself. Often inset from TrimBox.

The two that matter for production are TrimBox and BleedBox. Everything else is either the physical page (MediaBox) or a viewer convenience (CropBox, ArtBox).

The "boxes are equal" fail

Open an exported PDF and run a preflight. If it reports "no bleed present" or "BleedBox equals TrimBox," it means the exporter didn't write a separate BleedBox, which signals to the press RIP that the file has zero bleed.

This happens because most export dialogs hide the bleed setting inside a "Marks and Bleeds" panel that defaults to off. The artwork on screen might extend visually past the trim, but the PDF page box structure says otherwise, and the RIP trusts the structure.

Some shops will add the bleed by hand when they receive a file like this. Most won't. They'll send it back and ask for a corrected export. Either way, the file isn't press-ready.

How to fix it in Illustrator

File → Save As → Adobe PDF. In the PDF options dialog, open the Marks and Bleeds tab. Under "Bleeds," set the top/bottom/left/right values to your target (0.0625" for labels, 0.125" for most other print work, or whatever your print provider specifies). You can optionally check "Use Document Bleed Settings" if you already set bleed in the New Document dialog.

That's it. The resulting PDF will have a BleedBox that is larger than the TrimBox by the specified amount on each side.

How to fix it in InDesign

File → Export → Adobe PDF (Print). In the Export dialog, open Marks and Bleeds in the left-hand panel. Same setup: set the bleed values, optionally "Use Document Bleed Settings" if configured, click Export.

Note: the bleed value in the InDesign document setup (File → Document Setup) is the canvas guide. What you see on screen while designing. The Export dialog bleed is what gets written to the PDF. They should match, but setting one doesn't automatically set the other.

How to fix it in Affinity, CorelDRAW, and others

The general pattern is the same: the tool has a document-level bleed guide (for designing) and an export-level bleed setting (for the output file). In Affinity Publisher: File → Export → PDF → More → Include Bleed. In CorelDRAW: File → Export for Print → PDF → Prepress tab → Bleed limit. Always check the exported PDF's page boxes after export, because a surprising number of dialogs default the export bleed to 0.

Not sure which page boxes your PDF has?

Preflight reads all five PDF page boxes, measures bleed per side, and tells you exactly what's present and what's missing. In language you can hand to your client.

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TrimBox vs BleedBox: what's the difference?