# PDF or EPUB for reading on iPhone and iPad?

> Use PDF when the original page layout matters. Choose EPUB when you want text that adjusts to your screen and reading preferences. Reader accepts both formats.

Canonical page: https://reader.brighteng.org/guides/pdf-vs-epub/
Updated: 2026-09-28

## Start with what you need to preserve

For a paper with figures, a form, or a document whose page references matter, the original PDF layout can be useful. For a novel or another mainly text-based book on a small screen, EPUB’s adjustable text can make it easier to settle into a comfortable reading size.

The choice is limited by the files you can obtain legitimately. Reader imports both formats; it does not convert one format into the other or remove document protection.

## How the formats behave in Reader

| Question | PDF | EPUB |
| --- | --- | --- |
| Does the original page design stay in place? | Yes. The document controls the page typography and layout. | Text adapts to the reading view; source styling can affect the result. |
| Can I adjust the book’s text in Reader? | Reader does not re-typeset the PDF page. | Reading Settings includes EPUB text adjustments. |
| What does the reading theme change? | The controls and area surrounding the original page. | The reading view, including its text presentation. |
| Can I use passage actions? | When the PDF has usable selectable text. | When the passage contains selectable text. |
| Is an account needed for ordinary reading? | No ChatGPT account is needed. | No ChatGPT account is needed. |

## When a PDF looks right but selection does not

A PDF can be a collection of scanned images. Looking like text does not necessarily mean it has a selectable text layer. Even when text is selectable, its extraction order may differ from the printed layout, especially in multi-column documents.

Reader does not currently advertise built-in OCR. If passage selection is important, use a document with a suitable text layer or ask the publisher for an accessible EPUB. Do not assume an AI model can read text that the app cannot select.

## Keep the useful source

Try a few pages before committing to a long reading session. Check small text, diagrams, notes, and any passage you want to translate. Keep your original file outside the app so you can choose a different version later.

Next, [import your PDF or EPUB](/guides/import-pdf-epub/) or learn how to [use ChatGPT with selected text](/guides/chatgpt-reading-assistance/).