Why HTML is more accessible than PDF.
A PDF is a set of fixed pages, designed for printing. HTML is built to adapt to whoever is reading it: their screen, their zoom level, their screen reader, their language. That's why federal guidance tells agencies to default to HTML and use PDFs only when necessary.
What the federal government says
Section508.gov, the federal government's accessibility program, puts it directly: "Federal policy requires agencies to prioritize HTML and use PDFs only when necessary." 1 The White House's OMB memo M-23-22, Delivering a Digital-First Public Experience, encourages agencies to default to HTML, and Digital.gov's guidance on PDFs concludes that "most of what currently exists would be better delivered using HTML as a standard web page." 2
That guidance is written for federal agencies. The reasons behind it apply to every public website.
Where PDFs fall short, even good ones
Pages that don't reflow
A PDF keeps the layout of a printed page. Someone with low vision who zooms to 200% or 400% gets text too wide for the screen and has to scroll sideways for every line. HTML reflows: the text wraps to fit, at any size.
Phones
More than half of the people using government websites do it on a phone, according to Digital.gov. A letter-sized page on a phone means pinching and panning to read anything. HTML fits the screen.
Accessibility that depends on the reader's software
A PDF is only as accessible as its tags, and tags only help if the PDF reader uses them. Support varies between desktop readers, browsers' built-in viewers and phone apps. HTML works the same way in every browser, with every screen reader.
Tags that break
Tagging a PDF is skilled, slow work, and it's fragile. Editing the document, exporting it again from Word, or combining files into a packet can strip or scramble the tags. Most PDFs on government websites were never tagged in the first place.
Scans: the worst case
A scanned PDF is a picture of a page. There's no text in it at all, so a screen reader has nothing to read, search finds nothing, and translation has nothing to translate. More on making scanned PDFs accessible.
PDF and HTML side by side
| HTML | ||
|---|---|---|
| Zoom to 400% | Scroll sideways for every line | Text reflows to fit |
| On a phone | A printed page, shrunk | Fits the screen |
| Screen readers | Only if tagged, and the reader app supports the tags | Headings, lists and tables work everywhere |
| Your own colors and fonts | Rarely | Yes, through browser and system settings |
| Translation and read-aloud | Depends on the app | Built into browsers and phones |
| Scanned documents | An image with no text | Real text, once converted |
| Keeping it accessible | Every edit can break the tags | Structure is part of the page |
What Paridoc does about it
Paridoc gives every PDF on your site an HTML version, built from the document's own structure: headings, reading order, tables, lists and image descriptions, checked against WCAG 2.2 AA. When someone clicks a document link, the HTML is what they get. The PDF stays where it is, as the print copy, one click away. How it works.
- Section508.gov, Create Accessible PDFs.
- Digital.gov, Reduce, remove, remediate: PDFs and government websites, December 31, 2024.
Questions
Can a PDF be fully accessible?
Yes. A carefully tagged PDF can meet WCAG. But it takes skilled work on every file, the tags break easily when a document is edited or re-exported, and how well it works still depends on the reader's PDF software. Most PDFs on government websites are not tagged at all.
Why is HTML better on a phone?
HTML reflows: text wraps to fit the screen at any size, so nobody has to pinch, zoom and scroll sideways to read a line. A PDF keeps the layout of a printed page.
What does the federal government recommend?
Section508.gov says federal policy requires agencies to prioritize HTML and use PDFs only when necessary, and the White House's OMB memo M-23-22 encourages agencies to default to HTML. That guidance is written for federal agencies, but the reasons apply to every public website.
Do we still need the PDF?
Keep it. It's the print copy and often the record. Paridoc leaves it exactly where it is and one click away in the viewer. The HTML version is what people read on screen.
Updated September 2026
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