A PDF and a PDF/A belong to the same family; only one is an archive. PDF/A (ISO 19005) restricts what a PDF may contain until every font, colour profile, and metadata record it depends on sits inside the file, so it still renders on a machine that has never seen your fonts.
The short answer: open the PDF in a tool that can write PDF/A — the PDF Standards tool in Acrobat, the Archive export in LibreOffice, or a Ghostscript command — apply a conformance level, then validate the result. A file carrying "PDF/A" in its name that was never validated is just a PDF with a new name.
Check the File Before You Convert
Most of these requirements are settled before you open a converter.
- Fonts. Every font must be embedded; one that cannot be, for licensing reasons, fails the conversion or gets substituted.
- Encryption. PDF/A forbids it, so passwords and permission locks come off first.
- Scripts and media. JavaScript, audio, video, and external file references are stripped, or the file fails.
- Colour. Device-dependent colour needs a declared output intent.
- Transparency. PDF/A-1 does not allow it, so layers are flattened, which can change how a page looks.
- Level. 1b is the original profile, 2b adds transparency and OpenType fonts, 3b also embeds source files such as an invoice XML. The "a" variants add accessibility tagging, the "u" variants add Unicode mapping.
Route 1: Acrobat and Its PDF Standards Tool
Step 1: Remove the Protection
Open the file and clear the security first: File > Properties > Security, or the options in the Protect tool. Unlock only documents you own.
Step 2: Apply the Standard
Open Tools and find the standards tool — Apply PDF Standards in current builds, Preflight with the PDF Standards profile in older ones. Pick the level your archive requires and apply it; the report lists what was removed.
Step 3: Save Under a New Name
Write a separate file and keep the original. An archival copy that overwrote its source cannot be re-run when the required level changes.
Route 2: LibreOffice, Free and Offline
Open the PDF in LibreOffice Draw, then File > Export As > Export as PDF, General tab, tick Archive (PDF/A-2b) or Archive (PDF/A-3b), and export. Draw rebuilds the page as editable objects, so forms and heavy tables can shift — fine for a report, not for a 60-page catalogue.
Route 3: Ghostscript, for Batches
Ghostscript converts from the command line: -sDEVICE=pdfwrite, -dPDFA=2, -sColorConversionStrategy=RGB, and a compatibility policy flag that decides whether an incompatible feature aborts the run or is converted and reported. Expect to supply an output intent profile, and expect a validator error on the first attempt.
Validate the Output, Every Time
- veraPDF is free, open source, and offline: the desktop app, or verapdf -f 2b file.pdf on the command line. Its report names the failing rule and the object it applies to.
- Preflight in Acrobat runs the same checks against its PDF/A profiles.
- Your own eyes catch what validators miss: page count, selectable text, and a font list showing every font embedded.
Why a Converted File Still Fails
- A font could not be embedded, or the text was turned into outlines — outlines draw correctly and cannot be searched.
- Encryption was never removed, and the export inherited it.
- The level was wrong: transparency or an attachment carried into PDF/A-1b.
- No output intent, usually CMYK artwork with no profile declared.
- The page is a scan. It can validate and still be unsearchable, because the page is a picture. OCR has to run first.
Most of these are preparation problems: a scan without a text layer, pages out of order, three sections that should have been one file. PDF Agile is a Windows PDF editor that runs OCR, reorders pages, and merges files locally, so the document reaches the conversion clean and never leaves your disk on the way.
FAQ
Is PDF/A the same as a compressed PDF?
No. PDF/A governs what the file may contain; size is a separate job, and compressing a PDF/A can break the conformance you just paid for.
Which PDF/A level should I choose?
2b covers nearly everything produced today. When an archiving rule names 1b, use 1b; when records travel with a data file, such as an invoice and its XML, 3b is the profile built for that.
Can I edit a PDF/A file afterwards?
Yes, and it stops being conformant the moment you do. Re-apply the standard and validate again.
Do I need Acrobat Pro to convert PDF to PDF/A?
No. LibreOffice and Ghostscript both write PDF/A, and veraPDF validates for free. Acrobat's advantage is a guided interface and a report you can file.
Keep the validated file and its report together — the report is what an auditor asks for.
