When most people say “PDF”, they mean the standard PDF format. But PDF is actually a family of related formats, each optimised for different use cases. Understanding which one to use can save you significant headaches.
Standard PDF
The baseline format created by Adobe in 1993. Standard PDFs can contain essentially anything: embedded fonts, images, interactive form fields, JavaScript, multimedia, digital signatures, and more. They’re the right choice for most everyday use cases — reports, presentations, contracts, forms.
The current standard is PDF 2.0 (ISO 32000-2), though PDF 1.7 remains extremely common.
PDF/A — Archival PDF
PDF/A is a subset of standard PDF designed specifically for long-term archiving. The “A” stands for Archive. It was standardised as ISO 19005 and is required by many government agencies, courts, and institutions for document retention.
Key restrictions of PDF/A: no JavaScript, no encryption, no external dependencies, all fonts must be embedded, no audio or video content, and colour profiles must be embedded. These restrictions ensure the document can be rendered identically decades from now, regardless of what software or operating system is used.
Use PDF/A when: you’re submitting documents to government agencies, archiving legal records, working with libraries or academic institutions, or any situation where long-term preservation is required.
PDFRun supports conversion to PDF/A-1b, PDF/A-2b, and PDF/A-3b via the PDF to PDF/A tool.
PDF/X — Print-Ready PDF
PDF/X is a subset of PDF designed for reliable prepress data interchange — in other words, sending files to professional printers. The “X” stands for exchange. It ensures that when a printer receives your file, they get exactly what you intended: correct colours, properly embedded fonts, and the right bleed and crop marks.
Use PDF/X when: sending files to a professional print shop, creating marketing materials (brochures, business cards, posters), or preparing files for offset printing.
PDF/E — Engineering PDF
Less commonly known, PDF/E is optimised for engineering and technical workflows — CAD drawings, 3D models, geospatial data. If you’re in engineering or architecture, your PDF tool probably handles this automatically.
Which One Should You Use?
For most people, standard PDF covers 99% of needs. Convert to PDF/A only when explicitly required by an institution. Use PDF/X only when sending to a professional printer.
When in doubt, stick with standard PDF — it’s the most universally compatible format and works everywhere.