What Is PDF/A?
PDF/A is an ISO-standardized subset of the PDF format designed specifically for long-term digital preservation of documents. The “A” stands for “Archive.” While a standard PDF can reference external fonts, contain JavaScript, or rely on linked multimedia, a PDF/A file must be entirely self-contained so that it can be rendered identically on any system, decades from now.
Think of it this way: a regular PDF is a living document that can depend on its environment. A PDF/A is a time capsule — everything needed to display it is embedded inside.
Key Differences Between PDF and PDF/A
| Feature | Standard PDF | PDF/A |
|---|---|---|
| External font references | Allowed | Prohibited — all fonts must be embedded |
| JavaScript | Allowed | Prohibited |
| Encryption | Allowed | Prohibited |
| Audio/video | Allowed | Prohibited (PDF/A-1, PDF/A-2); limited in PDF/A-3 |
| Transparency | Allowed | Prohibited in PDF/A-1; allowed in PDF/A-2 and PDF/A-3 |
| Color management | Optional | Required — ICC profiles must be embedded |
| Metadata | Optional | XMP metadata required |
| Self-containment | Not required | Mandatory |
PDF/A Conformance Levels
There are three main versions of PDF/A, each building on the previous:
PDF/A-1 (ISO 19005-1:2005)
Based on PDF 1.4. The strictest version — no transparency, no JPEG2000 compression, no embedded files. Best for maximum compatibility with older validators and archives. Use this when a regulatory body specifically requires “PDF/A-1.”
PDF/A-2 (ISO 19005-2:2011)
Based on PDF 1.7. Adds support for transparency, JPEG2000 compression, and PDF/A-compliant attachments. This is the most commonly used level today and the default in the pdfs.to converter. It offers the best balance of features and compatibility.
PDF/A-3 (ISO 19005-3:2012)
Same as PDF/A-2 but allows embedding any file type as an attachment (e.g., XML data, spreadsheets, source files). Useful for hybrid documents like electronic invoices (ZUGFeRD/Factur-X) that embed machine-readable XML alongside the human-readable PDF.
Who Needs PDF/A?
- Government agencies: Many jurisdictions require PDF/A for official records, court filings, and regulatory submissions.
- Libraries and archives: The Library of Congress and national archives worldwide use PDF/A for digitized collections.
- Legal firms: Long-term case file storage often mandates PDF/A to ensure documents remain readable in perpetuity.
- Healthcare: Patient records and medical imaging reports may require archival formats under data retention laws.
- Finance: Audit trails, tax filings, and compliance documents benefit from the tamper-resistance of PDF/A.
How to Convert PDF to PDF/A with pdfs.to
- Open the tool: Go to pdfs.to PDF to PDF/A.
- Upload your PDF: Drag and drop or browse for your file.
- Select the conformance level: Choose PDF/A-1, PDF/A-2 (recommended), or PDF/A-3.
- Click Convert: The tool uses Ghostscript with device-independent color conversion and font embedding to produce a compliant file.
- Download: Your PDF/A file is ready. You can verify compliance with free validators like veraPDF.
Can You Convert PDF/A Back to Regular PDF?
Technically, a PDF/A file is already a valid PDF. Any PDF reader can open it. If you need to add JavaScript, encryption, or other features prohibited by PDF/A, you can simply re-save the file as a standard PDF using any PDF editor. The embedded fonts and ICC profiles will remain, which is actually a benefit.
Frequently Asked Questions
Does converting to PDF/A change how my document looks?
In almost all cases, no. The visual appearance is preserved. The conversion primarily affects internal structure: embedding fonts, adding ICC profiles, removing prohibited features, and adding XMP metadata.
Which PDF/A level should I choose?
If you are unsure, use PDF/A-2. It is the modern standard with broad compatibility and support for transparency. Only use PDF/A-1 if specifically required by a regulatory body, and PDF/A-3 if you need to embed non-PDF attachments.
Is PDF/A the same as a “read-only” PDF?
No. PDF/A prohibits encryption and JavaScript, but it does not prevent editing. A PDF/A file can be opened and modified in any PDF editor. To prevent editing, use password protection with the Protect PDF tool — though note that a protected file would no longer be valid PDF/A.