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PDF/A vs PDF: what is the difference?
By Himanshu Ranjan · Updated 8 November 2026
PDF/A is an ISO-standardized subset of PDF for long-term archiving. It must be self-contained, with fonts and color information embedded, and it bans features that can break over time, such as encryption, JavaScript, external content and audio or video. Use PDF/A for records you must keep readable for years, and normal PDF for everything else.
What PDF/A is
PDF/A is a version of PDF standardized by ISO as the ISO 19005 family for archiving and long-term preservation of electronic documents. The idea is that a PDF/A file should look the same decades from now, so it must contain everything needed to display it. A normal PDF may rely on fonts installed on your computer or on a link to something else; a PDF/A file may not.
What PDF/A forbids
According to Wikipedia, PDF/A excludes features that hurt long-term preservation.
The practical effect: a PDF/A file cannot be password protected, cannot run scripts and cannot depend on outside resources.
- Encryption
- Linked (non-embedded) fonts, including standard fonts such as Times and Helvetica
- JavaScript and executable file launches
- Audio and video content
- References to external content
- LZW compression
- Transparency in PDF/A-1 only; allowed from PDF/A-2
Parts and levels
PDF/A-1 (2005) is based on PDF 1.4. PDF/A-2 (2011) is based on PDF 1.7 and adds JPEG 2000, transparency, OpenType embedding and PAdES digital signatures. PDF/A-3 (2012) is like Part 2 but allows embedding other file formats. PDF/A-4 (2020) is based on PDF 2.0.
Conformance levels come in letters. Level a (accessible) adds tagged structure, Unicode mapping and language information. Level b (basic) requires only faithful visual reproduction. Level u adds Unicode mapping for all text and is defined for PDF/A-2. Most archiving workflows use PDF/A-2b.
When you need it and when you do not
Use PDF/A for contracts, records and documents that must stay readable for years, or when an authority or archive asks for it. Some organizations require it for submissions, so check their instructions. Do not use it for documents that must be encrypted, interactive or send-ready with fillable fields: those features are not allowed. This page does not give compliance advice.
Converting to PDF/A on a Mac
FileDial's Convert › PDF to PDF/A creates PDF/A-2b for archiving. Its note says links and form fields are flattened, so make a normal copy first if you need them. Run it locally; a legal or financial document should not go through an upload site. A 42 MB PDF compressed, OCR'd or turned into images in about 2 seconds on a MacBook, so size is rarely a barrier. If the PDF is a scan, use OCR first so the archived copy is searchable; see the OCR PDF guide.
If you need to keep a protected version too, remember PDF/A cannot be encrypted, so apply a password with Sign & Lock › Add password… only to a separate working copy.
- Duplicate the original PDF and keep it.
- Select the copy in Finder.
- Choose Convert › PDF to PDF/A in the dial.
- Open the new file and check text, images and fonts, then store it in your archive.
Mistakes and practical checks
The first mistake is assuming any PDF can simply be saved as PDF/A. A PDF that uses linked fonts, transparency under PDF/A-1, encryption or embedded media breaks the rules and has to be rebuilt, which is why conversion changes the file. Review the converted copy page by page, especially fonts, images and form fields.
The second is converting a scan without OCR. The Library of Congress notes that PDF/A files made from scanned images may not support text indexing or extraction. A scanned contract archived as pictures of pages cannot be searched years later. Run OCR first, see the OCR PDF guide, then convert.
The third is losing interactive elements. FileDial's PDF to PDF/A note says links and form fields are flattened, so a fillable form becomes a fixed page. If you may need to fill the form again, keep the original. If you need to sign, apply signatures before archiving; Sign & Lock › Verify signatures writes a report on signer, time and whether the file changed since signing.
The fourth is mixing it up with security. PDF/A bans encryption, so it is not a way to protect a file. If a document needs a password, archive an unprotected copy in a secure location, such as an encrypted disk, and keep a protected copy for sharing.
The fifth is skipping validation when it matters. If an authority requires strict PDF/A conformance, a converted file should be checked with a validator such as veraPDF, which the Library of Congress mentions. This guide cannot promise that any converted file will pass a particular institution's checks.
Finally, pick the level by need. Level b guarantees appearance, which is enough for most records. Level a adds accessibility structure and is worth the effort for documents that must be usable with screen readers.
Questions
Is PDF/A just a normal PDF?
It is a restricted subset. A PDF/A file is a valid PDF that any reader can open, but it must embed fonts and color information and may not use encryption, JavaScript, audio, video or external references. The restrictions exist so the document looks the same many years from now.
What does PDF/A-2b mean?
It means Part 2 of the standard, based on PDF 1.7, at conformance level b, which requires faithful visual reproduction. It is a common choice for archives. Level a adds accessibility structure such as tags and language information, and level u adds Unicode mapping for all text.
Can I password protect a PDF/A?
No. Encryption is prohibited in PDF/A, so a password-protected file cannot conform to the standard. You can keep a separate password-protected working copy for sharing, but that copy is no longer PDF/A. Store the archival version somewhere secure, such as an encrypted drive, instead.
Does converting to PDF/A change my document?
It can. Fonts get embedded, and in FileDial's case links and form fields are flattened, so a fillable form becomes a fixed page. Keep the original, convert a copy and review the result page by page, especially if the document contains forms or unusual fonts.