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What is PDF/A, and when do you need it?

Published September 28, 2026 by the ModifyPDF team

If you have been asked to submit a document “in PDF/A format”, you are probably dealing with a court, a government agency, a university or an archive. PDF/A is an ISO standard (ISO 19005) for PDFs that need to look exactly the same when they are opened decades from now.

Why ordinary PDFs aren’t enough for archives

A regular PDF can depend on things outside the file: fonts installed on the viewer’s computer, links to external content, scripts or embedded media that future software may not support. It may also be encrypted. Any of these can make a document display differently, or not at all, years later. PDF/A removes those dependencies so a file is completely self-contained.

What PDF/A requires

  • All fonts embedded, so text renders identically everywhere.
  • Device-independent color, declared with an output intent (commonly sRGB).
  • Standard XMP metadata describing the document and declaring its PDF/A level.
  • No encryption, no JavaScript, no audio or video, and no content that depends on external sources.

The PDF/A levels

PDF/A has several parts and conformance levels. The ones you will meet most often are:

  • PDF/A-1b: the original 2005 standard, based on PDF 1.4. The strictest and oldest; still requested by some systems.
  • PDF/A-2b: based on newer PDF features, allowing transparency, layers and JPEG 2000 images. The most widely accepted choice today.
  • PDF/A-3b: like 2b, but other files can be attached inside the PDF (for example, the spreadsheet a report was built from, or XML invoice data).
  • The “u” levels (2u, 3u) add a requirement that all text can be searched and copied as Unicode.

The letter “b” stands for basic: the document’s visual appearance is guaranteed. If the organization you are submitting to doesn’t specify a level, PDF/A-2b is a safe default.

How to convert a PDF to PDF/A

  1. Open PDF to PDF/A and choose your file. Conversion runs in your browser.
  2. Pick the level you have been asked for: PDF/A-1b, 2b, 2u, 3b or 3u.
  3. Download the converted file.

The converter adds the XMP metadata, sRGB output intent and identifiers the standard requires. Full compliance also depends on the source file. For example, if a font was never embedded in the original, it can’t be added afterwards. If a submission portal rejects the file, the most reliable fix is to export again from the original program (Word, for instance, has a “PDF/A compliant” option in its Save as PDF settings) and then convert.

Common problems

  • Password-protected files can’t be PDF/A. Remove the password first with Unlock PDF if you know it.
  • Damaged files that give errors in some viewers can be rebuilt with Repair PDF before converting.
  • Scanned documents convert fine to the “b” levels, but can’t meet the “u” levels unless they contain real text.