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Print · PDF/X

What is PDF/X?

PDF/X is the ISO standard for press-ready PDF exchange — the file your printer actually wants. Drop a file for a free structural scorecard — no signup.

ISO 15930 · validated in Preflight's Print module (strict version-claim matching + the determinable box/color/resolution/ink rules).

Version claim
GTS_PDFXVersion and the XMP claim, compared with strict level tokens — an X-1a file claiming X-3 (or vice versa) is flagged, never substring-matched.
Page boxes
TrimBox presence and correct box nesting (Trim/Bleed/Art inside Media) — the geometry a press imposes on.
Device color
Uncalibrated DeviceRGB usage, applying the different X-3 / X-4 rules for device color.
Resolution
Effective (placed) image resolution against print thresholds.
Ink coverage
Total Area Coverage (TAC) from content-stream color operators, including scn-set spot alternates.
Traceable
Anything a static parse can’t determine is reported not-evaluable with a reason — never an invented pass.

PDF/X (ISO 15930) constrains PDF so a press can run it without guessing: fonts must be embedded, the trim geometry must be defined, and color must be predictable for the output condition. The flavors differ mainly in color and transparency policy — PDF/X-1a (CMYK/spot, flattened), PDF/X-3 (adds ICC color management), and PDF/X-4 (live transparency and layers, PDF 1.6). A file claims its flavor in metadata; conformance is whether the bytes actually follow that flavor’s rules — which is what validation is for.

How to make a press-ready PDF/X file

  1. Ask your printer which flavor they want — X-1a for blind CMYK exchange, X-4 when live transparency and ICC color are in the workflow.
  2. Export with the matching preset — InDesign/Illustrator ship PDF/X-1a:2001 and PDF/X-4:2010 presets that set the claim, boxes, and font embedding.
  3. Define the trim — make sure the TrimBox (plus bleed) is set; a press cannot guess where to cut.
  4. Keep color inside the flavor’s rules — CMYK/spot for X-1a; ICC-managed color for X-3/X-4; avoid untagged device RGB.
  5. Validate the claim before you send — check the file against the exact standard it claims, and fix findings in the authoring tool.
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Frequently asked questions

What is PDF/X used for?

PDF/X (ISO 15930) is the standard printers ask for when they need a self-contained, unambiguous press file: fonts embedded, page geometry defined, color predictable at the RIP.

PDF/X-1a vs PDF/X-4 — what’s the difference?

X-1a is the strict blind-exchange flavor: CMYK/spot only, transparency flattened. X-4 keeps live transparency, layers, and ICC-managed color. Modern digital workflows increasingly accept X-4; legacy offset workflows often still want X-1a.

What happened to PDF/X-3?

X-3 introduced ICC-based color management to PDF/X. It still appears in European workflows, but most tools now export X-4, which supersedes it in practice.

Is PDF/X the same as PDF/A?

No — PDF/X targets press exchange, PDF/A targets long-term archiving. They share ideas (self-containment, embedded fonts) but have different rules; a file can conform to both.

How do I check if a PDF is really PDF/X?

A claim in the metadata is not conformance. Preflight validates the claim strictly — level-exact version matching, box rules, device-color rules — and reports anything not statically determinable as not-evaluable rather than passing it.

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What is PDF/X? The print-exchange PDF standard · Preflight