What Is PDF/A? Archiving PDFs the Right Way

What PDF/A Is and Why It Exists

PDF/A is a version of PDF designed for long-term archiving, standardized as ISO 19005. Its goal is simple but strict: a document should look and read exactly the same decades from now as it does today, no matter what software opens it. Governments, courts, libraries, and businesses use PDF/A to store records they must keep readable for years or, in some cases, permanently.

Self-Contained by Design

The core idea behind PDF/A is self-containment. A conforming file must embed everything it needs to render, most importantly its fonts, so it never depends on software that might not exist in the future. If a font were merely referenced rather than embedded, a reader lacking that font might substitute a different one and silently change the document's appearance.

For the same reason, PDF/A bans features that reach outside the file or behave unpredictably: no encryption, no JavaScript, no audio or video, and no links to external content or fonts. Color must be defined in a device-independent way, often with an embedded color profile, so shades render consistently across screens and printers. The result is a stable, standalone snapshot of the document.

PDF/A-1, PDF/A-2, and PDF/A-3

The standard has grown in parts. PDF/A-1, published in 2005 and based on PDF 1.4, is the strictest and most widely required. PDF/A-2, based on PDF 1.7 (ISO 32000-1), added conveniences like JPEG2000 compression, transparency, and the ability to embed other PDF/A files. Each newer part relaxes some limits while keeping the archival guarantees intact.

PDF/A-3 is the notable exception: it lets you embed any file type, such as the original spreadsheet or XML behind an invoice, inside the archived PDF. That flexibility is powerful for e-invoicing but controversial for pure archiving, since the embedded file itself is not required to be archival. Choose the version your archive or regulator specifies.

Conformance Levels: a, b, and u

Within each part, conformance levels describe how complete the file is. Level B (basic) guarantees the visual appearance is preserved. Level A (accessible) adds tagged structure, so the reading order and semantics are machine-readable, which helps screen readers and future reuse. PDF/A-2 and later also define level U, which requires that all text carry Unicode mappings so it can be searched and copied reliably.

How to Convert a File to PDF/A

Most PDF software can save or export to PDF/A. In Adobe Acrobat, use Save As Other then Archivable PDF (PDF/A), or run the Preflight tool to convert and verify against a chosen profile. Office applications can often Save as PDF with a PDF/A option in the settings. Free tools and our top-rated PDF tools may offer a PDF/A export as well.

After converting, validate the result. A dedicated PDF/A validator, or Acrobat's Preflight, checks that fonts are embedded, no banned features remain, and the file truly conforms, rather than just carrying a PDF/A label. Start from a clean, born-digital source with real fonts where possible; scanned pages should be run through OCR so the archive contains searchable text, not just images.